Bah, don't know how to play this one:

[tlow03]

This is pretty tought because he is never really defining his hand by simply calling your flop bet and betting after you show a lot of weakness is a play he might make no matter what hes holding.. A couple of explanations that I could think of are the
a. he was playing a under pocket pair and was tryin to pick up pot after your check
b. he had a monster and was milking you.
c. ace high trying to pick up the pot

Personally I pull the trigger twice on this and bet the turn also hoping that the villian will fold. A lot of times players will abandon a draw on the turn to a pot sized bet or reraise if they were slow playing. Checking here doesn't help you figure out what hes playing. Just my 2 cents.