I would have checked flop too.

Now I call, and I want to say c/c river. I really don't have a feel for how smart/aware/knowledgeable these players are. Seems like he should never be stacking off as a bluff, but maybe he has a smaller flush or AK/A8 for a good 2pair. Hard to put him on just 88/A5 and seems unlikely he'd call a push with anything worse, except maybe QhJh I guess.