AQs OOP making TP on the turn

[Imrahil]

Villain is unkown:

PokerStars No-Limit Hold'em, $0.25 BB (6 handed) Hand History Converter Tool (http://poker-tools.flopturnriver.com/Hand-Converter.php) from FlopTurnRiver.com (http://www.flopturnriver.com) (Format: 2+2 Forums)

CO ($23.80)
Button ($25)
Hero ($49.80)
BB ($34.45)
UTG ($8.05)
MP ($27.15)

Preflop: Hero is SB with Q/images/graemlins/spade.gif, A/images/graemlins/spade.gif. UTG posts a blind of $0.25.
UTG (poster) checks, <font color="#666666">1 fold</font>, CO calls $0.25, <font color="#666666">1 fold</font>, <font color="#CC3333">Hero raises to $1.5</font>, <font color="#666666">1 fold</font>, UTG folds, CO calls $1.25.

Flop: ($3.50) 7/images/graemlins/heart.gif, 6/images/graemlins/spade.gif, 2/images/graemlins/club.gif <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $2.25</font>, CO calls $2.25.

Turn: ($8) A/images/graemlins/club.gif <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">CO bets $4.5</font>, Hero calls $4.50.

River: ($17) 6/images/graemlins/heart.gif <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">CO bets $9.25</font>, Hero?

[Sir Winalot]

Easy call.

[BombayBadboy]

Yup, call but I'd do it reluctant. You are getting good odds and you have TPGK, but once he bet the turn and you called he has got to give you credit for atleast an ace if he is decent. Against an unknown its still a call though.

[HNIC]

as another poster said I think this is an easy call. Seems to me he may be representing and ace.

Why check/call the turn?