10NL top pair + flush draw: call or raise?

[pokahpaul]

villain is running 85.7/14.3/3.75 over 20 hands.

PokerStars No-Limit Hold'em, $0.10 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

UTG ($24.25)
MP ($14.75)
CO ($9.30)
Button ($9.55)
SB ($12.90)
BB ($2.80)

Preflop:
UTG calls $0.10, MP calls $0.10, CO calls $0.10, <font color="#CC3333">Button raises to $0.8</font>, <font color="#666666">2 folds</font>, UTG calls $0.70, MP calls $0.70, CO folds.

Flop: ($2.65) A[img]/images/graemlins/diamond.gif[/img], 2[img]/images/graemlins/heart.gif[/img], 4[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">UTG bets $0.9</font>, MP folds, <font color="#CC3333">Button raises to $3.1</font>, UTG folds.

Final Pot: $4.45

should i have just flat called his bet?
if so, do i always flat call against all types of villain?

looking at this hand, i'm convinced that there's more value in calling and raising if he fires a second barrel on turn.