Wow, I actually had the same situation happen to me yesterday against a decent player. I pushed the flop figuring he'd fold AA, villain called instantly with AKo.

It seems a lot of people are willing to make a huge three bet with AK.

I also had someone 3 bet my queens and I put him on AJ-AK, I pushed the rag flop, He called with AKs on a flush draw that didn't get there.