Half your stack on a suited ace?

Third level in the Party Friday Special. Villian hasn't been at table long so I am without any reads.

Party Poker No-Limit Hold'em Tourney, Big Blind is t30 (10 handed) FTR converter on zerodivide.cx

saw flop
UTG (t1200)
UTG+1 (t865)
UTG+2 (t3405)
Hero (t1075)
MP2 (t1125)
MP3 (t2985)
CO (t1710)
Button (t555)
SB (t1735)
BB (t610)

Preflop: Hero is MP1 with 7[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/spade.gif[/img].
<font color="#666666">3 folds</font>, Hero calls t30, <font color="#666666">4 folds</font>, SB completes, BB checks.

Flop: (t90) A[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/diamond.gif[/img], J[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, BB checks, <font color="#CC3333">Hero bets t55</font>, SB folds, <font color="#CC3333">BB bets t580 (all in)</font>, Hero ???

I think this is a bluff or semibluff often enough that I should call. Also this could be a jack or worse ace. Who's making the call here?