Unusual semi bluff, good or bad

[BobboFitos]

PStars .5/1. I'm in the big blind with ~110, MP has 70, SB just sat and bought in the max. (But he's not important)

I get dealt 4 [img]/images/graemlins/spade.gif[/img] 4 [img]/images/graemlins/diamond.gif[/img]

Folded to MP, who raises to 4$. SB calls, I call. Pot 12$ minus rake.

I've never played with SB, MP is aggressive who likes to open raise when folded to him with a wide array of hands, but he's a good player.

Flop comes A [img]/images/graemlins/diamond.gif[/img] 5 [img]/images/graemlins/diamond.gif[/img] 3 [img]/images/graemlins/club.gif[/img]
SB checks, I check, MP bets 12, SB quickly folds. I push.

Comments appreciated...