The only reasonable hands I could put him on that beats you is TT or 99 and those are raised pf more often than not, esp in 6 max (I am assuming this is 6 max?). I guess it's also very possible he limped JJ, hit top set on the flop and just slow played it to the end. I really don't think he has a str8 here. Without any solid reads on villain, however, I would have called this bet...