my only read is that he DIDNT reraise AK preflop and showed it down earlier vs another player.
Oh, I think I misunderstood this comment: He didn't "voluntarily" show AK, he went to showdown. So, he wasn't pulling some "look I had AK and didn't re-raise it pre-flop".

I would have to have been 3-betting light repeatedly vs. this guy before I call with QQ... but maybe I am a nit.