$6 NLTRN: Playing trash in an unraised pot

[Somekid]

This is about the 7th hand in, but my read on my opponent is that he's somewhat loose passive. A few hands ago he had called my 2/3 pot CB with KTo on a 4-Q-3 rainbow flop. I only fired on the flop and then he checked down after calling. So I concluded he's somewhat loose with his flop calls and a bit passive.

Should I have just not gotten involved in this hand since the pot is so small, or is my play okay.

PokerStars No-Limit Hold'em Tourney, Big Blind is t20 (2 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Hero (t1660)
Button (t1340)

Preflop: Hero is BB with 6[img]/images/graemlins/club.gif[/img], 4[img]/images/graemlins/diamond.gif[/img].
Button calls t10, Hero checks.

Flop: (t40) 3[img]/images/graemlins/club.gif[/img], 4[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets t40</font>, Button calls t40.

Turn: (t120) 5[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets t80</font>, Button calls t80.

River: (t280) 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">Button bets t220</font>, Hero folds.

Final Pot: t280