I usually check behind here as well, but maybe I give my callingass opponents too much credit. This was a horrible call by the guy. I'll be he was crossing his fingers that you were a whiffed AK bluffing the straight draw. I have to think that usually this is a bad bet because usually he's only calling with a better hand. In his place I check/call that river with a set and a 6 only.

Whats up with your preflop raise?
Whats up with his flop call??