Mint most certainly does NOT mean warped - would you accept a new album in such condition? The seller owes you a refund, plain and simple.
Believe it or not, there are several Ebay workshops on this subject.
Basically, you can insist on the seller taking it back for a refund under one or both of two criteria:
1.) If it's obvious that the record was poorly packed (didn't arrive in a proper "box type" media mailer.)
2.) If the seller graded it using the Goldmine system, in which case the seller should have given it an "F" which is the "trash" category. If it received anything higher, the seller was misrepresenting.
Most sellers, especially large volume sellers don't want negative feedback, and would just as soon take it back (some just say keep it and give you a refund anyway!) This is especially true if the total cost including postage was under $25 -- it's just not worth the bad press to them. Additionally, most sellers don't test-play records, and it's sometime not obvious visually that a record is warped, so they'll give you the benefit of the doubt.
I can't even count how many LPs I have bought brand new sealed that have come out of the packaging warped--dozens and dozens--a handful have been unplayable. It was so bad fron one local store that that after returning many and getting more warped vinyl in exchange, I have been hardcore boycotting them for a couple years now. I think they and their distributors were both being idiots about storing them. This store certainly wasn't the only source for bad vinyl--most distros leave vinyl sitting in hot trucks, I'm sure.
This is a sore spot for me too living in Texas. Nearly every album I buy from local stores is warped to some degree. Most are still playable, but it still bothers me. I'm also in the wine business and deal with this regularly from distributors trying to sell cooked wine. Just last month I was talking with a trucking company that regularly delivers wine to Austin in the summer and they admitted they never use refrigerated trucks. That means the wine is transported thru Death Valley at who knows what temp with no real protection. Either way I think it's bad business and tries to take advantage of people. I don't think the local record stores and wine distributors like me too much but until they start taking their own business more seriously I don't care. However, with Ebay, and a sealed album, I'd have some trouble expecting a refund from a small private seller that had no way to know if the album was warped. A big store on Ebay I would expect more help from. Personally, if I sold a sealed album to someone and it turned out warped I would refund their money with no issues as otherwise, no matter what my good intentions were, I sold a product that was not what they were expecting. I wouldn't feel right about that.
I purchased a tull record for $65.00 from a large seller on ebay that was sealed. He even puts in his ads that because the record was sealed he gives no warranty and you can't return it. Ebay did not agree with the seller and forced him to refund my $65.00. Get your money back. I would also like to agree with some of the other posts. Many sellers give you the refund.
Just because "I had to have it" I paid, with shipping, nearly $90 or so for an "excellent" copy of Tull's "Stand Up" 1st edition pink Island label UK pressing. Turned out it has audible surface noise, no matter how many times I wet vac it.
Debatable whether it sounds any better than my U.S. Reprise label early pressing.
All in all, buyer beware with ebay used records out of the UK.
I always ask the seller if the record is open if he has a turntable would he put it on and verify if it is warped or not. Yeah I know but today a turntable is not an item many people still have in this digital age(sad)and if he tells you it is not warped and it arrives warped then it could have been caused during shipping.You can't expect the seller to open a sealed copy ,it deminishes the value of the recording. If it is an album you covet and have been searching for a while( took me 20 years to find a sealed copy of Master Apprentice) then over night shipping is the only way.If you have a record delivered overnight or next day and it is warped then demand a refund. If you purchase a record at a music store ask them if they they have a turntable to check what you are buying is not warped. At least take it out after purchase and lay it on the inside sleeve on their counter to tell if it is warped beyond play. If it is warped beyond play ask for another one. Tell them they have an option to keep opening copies ( if it is a current release) until you find a no warped record or until you get a refund. Beware record stores CANNOT RETURN RECORDS TO MANUFACTURE they are stuck with what they buy. This protects BOTH parties because if the record leaves the store unwarped and lands on your turntable warped then you caused it by leaving it in the sun or whatever. As far as surfave noise some sellers offer to clean the record for a nominal fee and you can't expect them to play every record they sell. Let's get real these people find these records at swap meets,thrift stores,record stores,garage sales,estate sales etc. There trying to turn a profit that's why they are on Ebay.