Flop set OOP in unraised pot

[Godfather80]

Texas Hold'em $0.25-$0.25 NL (real money), hand #1,426,554,033
Table Riverside, 1 Nov 2005 06:58 PM

BB ($27.30 in chips)
UTG (Hero 4[img]/images/graemlins/spade.gif[/img]4[img]/images/graemlins/heart.gif[/img]) ($28.50 in chips)
UTG+1 ($26.15 in chips)
UTG+2 ($28.95 in chips)
MP1 ($37.70 in chips)
MP2 ($20.60 in chips)
CO ($25 in chips)
Button ($30.90 in chips)
SB ($9.65 in chips)

ANTES/BLINDS
SB posts blind ($0.15), BB posts blind ($0.25), CO posts blind ($0.25).

PRE-FLOP Hero is dealt 4[img]/images/graemlins/spade.gif[/img]4[img]/images/graemlins/heart.gif[/img]
Hero calls $0.25, UTG+1 folds, UTG+2 calls $0.25, MP1 folds, MP2 calls $0.25, CO checks, button folds, SB calls $0.10, BB checks.

FLOP ($1.50) 4[img]/images/graemlins/diamond.gif[/img]9[img]/images/graemlins/diamond.gif[/img]3[img]/images/graemlins/spade.gif[/img]
SB bets $0.50, BB folds, Hero?

[i][b]What raise is standard here?[b][i]