50NL Two pair with flush draw on board

[gman339]

Is this line standard or should I be worried about a set or better 2pr with villain's smallish bets?

Full Tilt Poker, $0.25/$0.50 NL Hold'em Cash Game, 9 Players
LegoPoker Hand History Converter

MP2: $111.05
CO: $25.10
Hero (BTN): $39.85
SB: $39
BB: $87.60
UTG: $178.55
UTG+1: $51.05
UTG+2: $49.25
MP1: $42.45

Pre-Flop: 8[img]/images/graemlins/heart.gif[/img] A[img]/images/graemlins/diamond.gif[/img] dealt to Hero (BTN)
4 folds, MP2 calls $0.50, CO calls $0.50, Hero calls $0.50, SB calls $0.25, BB checks

Flop: ($2.50) 8[img]/images/graemlins/spade.gif[/img] 9[img]/images/graemlins/diamond.gif[/img] 4[img]/images/graemlins/spade.gif[/img] (5 Players)
SB checks, BB checks, MP2 checks, <font color="red">CO bets $0.75</font>, <font color="red">Hero raises to $2</font>, SB folds, BB calls $2, MP2 folds, CO calls $1.25

Turn: ($8.50) A[img]/images/graemlins/club.gif[/img] (3 Players)
BB checks, <font color="red">CO bets $2.50</font>, <font color="red">Hero raises to $25</font>