Cartridge distorting progressively during playback

Has anyone experienced this in their setup.  Record plays fine at beginning but begins to distort ( especially in midrange).  Here is the hitch.  It plays fine if you start with the first song middle or last.  But after a while the distortion progresses.
If you lift the tonearm and wait around 30 sec or more and lower to play the distortion disappears but will return in the next few mins.  It will do this if you re cue the same track or one near the beginning or end.

I have tried two phono stages and it does the same with both.  I tried a different cart (MC) and it does not do this.  

The cart in question is an Ortofon 2mBlack that is brand new.  It was set up the same as the previous 2mBlack it replaced under warranty (cartridge pin came off). SRA at 92, 1.5g tracking force.   Tracks perfectly.

Any insights on what is going on.  I figured I'd get some input before I take this back to the dealer.  Maybe there's something I overlooked. 
Couple of questions - does it distort in both channels or only one?

Did you set up the cartridge?  Have you rechecked all the setup parameters?
Check to make sure the tonearm or its cables are binding....If you checked the setup et al, send the cart back for an inspection.  I've had a couple of bad Orofons (one of which was replaced by a defective Ortofon - but returned and another was sent ok)
It defies all sense, reason, and logic for you to suffer such an extreme problem with your phono cartridge and yet after coming hear for advise you state, declare, and pronounce that this cartridge "Tracks perfectly." 
@pops, I set up myself, checked and rechecked.  Calibrated scale, usb microscope, loupe.  Distortion is both  channels.

@stringreen,  checked all cables and connections.  I was a little puzzled by the possibility of two defective carts in a row, given I have never had a single warranty issue before.  Now suddenly two in a row??  At least I know someone else had two bad apples too,

@clearthink, pretty much what I'd expect from you.

Thanks for the replies so far.
It can also be the stylus, coil or suspension having problems. But you cartridge is brand new so it really shouldn't be unless it's a manufacturer defect.
@vasaudio, would any of those things cause static problems?  No problems with first cart and static issues as soon as new cart installed.  And yes, all connections correct.  
Have to agree with @clearthink. Think about it from a humorous angle.
Sounds like the arm bearing is sticking. Are you sure the rear of the tonearm is clear of the cue mechanism?
@nutella it sounds like a defective cartridge to me - unlucky! I have a similar situation with my Transfiguration Proteus except my problems started after 500 or so hours - you can check the thread  "cartridge issues."

Like you I am pretty savvy with setup and tried everything - several times. What tonearm are you using? noromance has a good suggestion.
Thanks @pops , I'll check out that thread.  I won't have a chance to get to the dealer until the weekend so that will give me some more time to troubleshoot.

@noromance , no problems laughing about it.  Just not how I planned to spend Sunday afternoon.  Clearthink likes to describe in groups of three words.  That is what I expect to see when he posts.