25NL nut flush on double paired board

Wasn't sure what to do on this hand, felt I played it too passively. Villain just sat down, seems like average 25NL donk.

Party Poker No-Limit Hold'em, $ Hero (6 max, 5 handed) converter

saw flop|<font color="#C00000">saw showdown</font>

<font color="#C00000">Hero ($26.25)</font>
UTG ($26.75)
MP ($17.45)
Button ($24.14)
<font color="#C00000">SB ($39.80)</font>

Preflop: Hero is BB with 4[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/spade.gif[/img]. SB posts a blind of $0.10.
UTG calls $0.25, <font color="#666666">2 folds</font>, SB (poster) completes, Hero checks.

Flop: ($0.75) 2[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets $0.5</font>, Hero calls $0.50, UTG calls $0.50.

Turn: ($2.25) 2[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets $0.75</font>, Hero calls $0.75, UTG calls $0.75.

River: ($4.50) K[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets $3</font>, Hero calls $3, UTG folds.

Final Pot: $10.50

Results in white below: <font color="#FFFFFF">
Hero has 4s As (flush, ace high).
SB has 5c Ts (full house, fives full of twos).
Outcome: SB wins $10.50. </font>