400nl. Full ring on stars.

Villain is somewhat passive post flop. I have a note on him that says that his checks aren't always a sign of weakness. He's roughly 19/7/1.75. I think. don't have PT up and going on what I think i remember seeing last night. He's a decent enough player, even if he's somewhat passive, and I haven't seen him getting out of line before.

I limp [9d] UTG. I know a lot of you raise this, but in full ring I'd rather not raise as much stuff in the first two spots. folds to him in LP and he makes it $20. I call.

$43 pot. HU. flop comes [Kc][7h]. check check.
turn is the . check check.
river is the . I bet $32. he raises to $162. I fold.

thoughts?

you're a nit