I might raise/fold the turn ... it seems unlikely that the 4 could have helped the villian (doubtful he limped with K4, Q4 ... maybe he could have limped with 44). It seems way more likely that the villian just picked up a club draw and wants to pump the pot ... you might even get a hand like KJ to fold to 2 big bets (unlikely .. but possible). If we're 3-bet on the turn, I think we can safely release.

EDIT :

I'm not so sure about the safely release part anymore ...