[M.B.E.]

You have a point: if he's got nut spades he played it kind of weirdly, but I still wouldn't rule that out. Some players just aren't going to push there with a nut flush draw, especially after your reraise was so small; they'll just call and peel.

So I think it's possible he has spades, but more likely he's got AT. Based on that, you need to make a bet on the turn (maybe 600) and fold to any raise.