too large of a bet on the flop. I wouldn't check the turn if you had made a smaller bet on the flop. Villain with JJ most likely plays this hand the same way. If i'm in villains position and you continuation bet the size of the pot at the flop, I am suspicious that you are trying to protect your hand or that you missed, so I call, then you check the turn, well I'm definitely betting, because now my I believe my JJ is good.

This isn't to say that the opponent couldnt have pocket A's, K's, AK, or possibly KQs but this hand could have been played better at the flop.