Overcard + FD vs. AI on Flop (math confirmation)

[skates]

Full Tilt Poker - No Limit Hold'em Cash Game - $0.10/$0.25 Blinds - 5 Players - (LegoPoker HH Converter)

Hero (SB): $44.85
BB: $7.55
Villain (UTG): $14.05
CO: $10.20
BTN: $28.70

Preflop: Hero is dealt A[img]/images/graemlins/club.gif[/img] 9[img]/images/graemlins/club.gif[/img] (5 Players)
Villain calls $0.25, 2 folds, <font color="red">Hero raises to $1.25</font>, BB calls $1.00, Villain calls $1.00

Flop: ($3.75) 3[img]/images/graemlins/club.gif[/img] 7[img]/images/graemlins/spade.gif[/img] T[img]/images/graemlins/club.gif[/img] (3 Players)
<font color="red">Hero bets $2.00</font>, BB folds, <font color="red">Villain raises all-in to $12.80</font>, Hero???

I called following this logic:
It costs me ~$11 to call into a pot of ~$28 which means I only need to win something like 40% of the time, which I assumed I had by counting the 3 aces as outs (12 outs then, which means I win something like 45% of the time). Is this correct? Or is my math too approximated and too reliant on the aces as outs. (I figure at the very worst, I'm like 33% to win if he has a set, and there's still a good shot that my 9 is an overcard). The guy started flaming me, but I thought it was the right call. Was I correct?