$50NL AQs - Calling a 3bet

[Tawbor]

Villain 20/8 not seen him 3bet before (50 hands only), Hero most aggro player at the table and have 3bet several times lately.

Full Tilt Poker, $0.25/$0.50 NL Hold'em Cash Game, 5 Players
LeggoPoker Hand History Converter

BTN: $78.40
SB: $50.35
BB: $50.75
Hero (UTG): $50
CO: $42.85

Pre-Flop: A[img]/images/graemlins/heart.gif[/img] Q[img]/images/graemlins/heart.gif[/img] dealt to Hero (UTG)
<font color="red">Hero raises to $2</font>, 2 folds, <font color="red">SB raises to $6.50</font>, BB folds, Hero calls $4.50

Flop: ($13.50) A[img]/images/graemlins/club.gif[/img] 4[img]/images/graemlins/spade.gif[/img] 3[img]/images/graemlins/heart.gif[/img] (2 Players)
SB checks, Hero checks

Turn: ($13.50) 8[img]/images/graemlins/diamond.gif[/img] (2 Players)
SB checks, <font color="red">Hero bets $9</font>, <font color="red">SB raises to $18</font>, Hero ?