x/r : OverPair on 5J4s > fold too nit ?

When you make the cbet otf, you should think "what do I do if he raises?" before you bet.

That board is great for semibluff check-raise, as your 3bet range misses the board so often. Normally the top of your range is overpair+fd, and if he has Ac or Acc in his hand you just have to fold a ton to his raise.

The thing is that most of the time the best case scenario is Jxxx, and against that range you are flipping. The fact that he isn't raising for a pot looks more like a valueraise to me, as with bluff he would want to maximize his folding equity. Of course on the other way around it gives him good odds for the bluff if he is having a total bluff.

I would fold and keep an eye on how he plays those "miss your range"-boards. When you pick up more hands on him, you will see if he likes to attack them or not.