Ever fold on the flop? Is there ever a flop or a circumstance that would force you to let go of the almighty pocket aces?

I was told today by another player that he folded aces when faced w/ to a flop of because he said he knew he was beat.. Now I had played w/ this guy for a couple of hours and he was a 98%er on OPR so I started to believe him but what do you think?? I asked him to send me the pic or to post it on here and he agreed, so we will just have to wait and see if it happens.. It was for all of his chips if that helps..