Set on Monotone Flop

[El Maximo]

I did a search and found this scenario is discussed occassionally. What's the best play here:

$10+1 NL SNG

Party Poker No-Limit Hold'em Tourney, Big Blind is t30 (10 handed) converter

MP1 (t710)
MP2 (t665)
MP3 (t995)
CO (t565)
Button (t1000)
SB (t575)
Hero (t775)
UTG (t1025)
UTG+1 (t815)
UTG+2 (t875)

Preflop: Hero is BB with 3[img]/images/graemlins/spade.gif[/img], 3[img]/images/graemlins/club.gif[/img].
UTG calls t30, UTG+1 calls t30, UTG+2 calls t30, MP1 calls t30, MP2 calls t30, <font color="#666666">2 folds</font>, Button calls t30, <font color="#666666">1 fold</font>, Hero checks.

Flop: (t225) 4[img]/images/graemlins/diamond.gif[/img], 3[img]/images/graemlins/diamond.gif[/img], 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(7 players)</font>
<font color="#CC3333">Hero bets t125</font>, UTG folds, UTG+1 calls t125, UTG+2 folds, MP1 calls t125, MP2 folds, <font color="#CC3333">Button raises to t500</font>, Hero ??

At this level this raise could mean flush, flush draw, or complete bluff. Im leaning towards flush draw and if he has a made flush I still have outs. Anyone else push here?