Shipping amps upside down?

I recently recieved a used amp that was shipped upside down. The sender will remain nameless as he is a decent guy and went out of his way to get it to me quickly. However the fact remains that the address label/postage was on the bottom of the box (which was the top for the entire trip, even with all the *up* arrows pointing the wrong way) The trip was probably close to 3000 miles, but was shipped essentially 2 day air. I cannot hear any parts rolling around and it performs like it is supposed to as far as I can tell (but volumes are low right now as the wife and kids are sleeping) I have heard horror stories about electronics being shipped upside down. But in my case should I worry or not? The amp is SS but it weighs in at 50 lbs. Could there have been damage that will show up in the near or far future? If I sell this amp in 2,5,10 years should I still be concerned about it? Sending it back to the factory for a check-up probably involves another 6000 miles of travel. Would more harm than good be done by that?

It just bothers me to have to worry about something like this.