any reads on what he has been limp calling with preflop? What about how often he slow plays? Also how aggressive were you being?

His turn check is kinda weird because I would expect him to be betting any ace in his range and all sets in his range, which is basically his entire range at this point.

The only thing I can think of is he was either going for a check raise on the turn /w AJ/set or maybe he has KK/QQ and turned his hand into a bluff since maybe he thinks its unlikely you have an ace on the river.

Def a fold though.