QQ vs. A high flop heads - up on the flop

I only ended up with 7 hands with Opponent before he got up and left. During that time he played a couple of hands and I didn't see any showdowns. So, no reads.

Party Poker 2/4 Hold'em (10 handed) FTR converter on zerodivide.cx

Preflop: Hero is Button with Q[img]/images/graemlins/spade.gif[/img], Q[img]/images/graemlins/heart.gif[/img].
<font color="#666666">7 folds</font>, <font color="#CC3333">Hero raises</font>, <font color="#666666">1 fold</font>, BB calls.

Flop: (4.50 SB) 5[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">BB bets</font>, <font color="#CC3333">Hero raises</font>, BB calls.

Turn: (4.25 BB) A[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">BB bets</font>, Hero ?