99 from BB vs shortie

[DandyJam]

Full Tilt 6-max. Blinds $0.5/1.

Button is shortstacked with $30. No real good read on him but he seems like a decent, somewhat loose player. I haven't seen him go out of line yet. My table image is probably slightly LAG, but I haven't been very aggressive although I've played quite a lot of hands.

All fold to button who limps. SB calls. I raise to $4 from BB with 9 [img]/images/graemlins/heart.gif[/img]9 [img]/images/graemlins/spade.gif[/img]. Button calls, SB folds.

Flop: Q [img]/images/graemlins/diamond.gif[/img]4 [img]/images/graemlins/club.gif[/img]3 [img]/images/graemlins/heart.gif[/img] (Pot: ~$9)

I check. Button bets $6. He has $20 left after his bet. I check-raise all-in.

Good or bad? Should I just have bet the flop instead, in which case I would probably be committed to call a push from the button. I figured my best way to get some more money from him would be to let him take a stab at the pot if checked to.

Edit: The flop did not contain a flush draw