How active had you been at the table with him?? Was he just playing back at you for an earlier hand??

He could easily be betting his King with high kick....Thats a pretty strong bet on the turn if he has a set you'd think he would go lighter to try and keep you in the hand.
There are a number of hands that beat you that he could have called with (44, JJ,) He probably wouldve reraised with KK and probably wouldnt call with KJ?
I think you need to call and see the river.