NL50 slowplay this villain?

[Johnes Benjamin]

Villain was running at 61/10/.6 over 150 hands.
I would normally raise this immediately to try and build up a big pot against an A. However, I didn't know about this spot. Villain has played so passively so far his bet on the flop seemed much more like he was trying to take me off a hand, I didn't feel as though he would come out and pot the flop with any A other than a very weak one he was uncomfortable with.

Of course, b/c he is passive he hasn't bluffed a lot so I can't expect him to necessarily fire multiple barrels.
What do you guys think of just calling this flop?






Poker Stars - No Limit Hold'em Cash Game - $0.25/$0.50 Blinds - 6 Players - (LegoPoker Hand History Converter)

SB: $53.75
BB: $29.55
Hero (UTG): $77.40
MP: $54.05
CO: $65.00
BTN: $63.75

Preflop: Hero is dealt 4[img]/images/graemlins/club.gif[/img] 4[img]/images/graemlins/diamond.gif[/img] (6 Players)
<font color="red">Hero raises to $2.00</font>, 3 folds, SB calls $1.75, BB folds

Flop: ($4.50) 9[img]/images/graemlins/spade.gif[/img] 4[img]/images/graemlins/heart.gif[/img] A[img]/images/graemlins/club.gif[/img] (2 Players)
<font color="red">SB bets $4.50</font>, <font color="red">
Hero wonders if villain needs to hang himself here