Is this an acceptable laydown vs. an unknown?

Ultimate Bet No-Limit Hold'em Tourney, Big Blind is t100 (8 handed) converter

UTG (t1365)
UTG+1 (t1435)
MP1 (t1475)
MP2 (t2260)
CO (t3240)
Button (t1475)
SB (t1040)
Hero (t2710)

Preflop: Hero is BB with A[img]/images/graemlins/diamond.gif[/img], J[img]/images/graemlins/heart.gif[/img].
<font color="#666666">2 folds</font>, MP1 calls t100, MP2 calls t100, CO calls t100, Button calls t100, SB completes, Hero checks.

Flop: (t600) 5[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(6 players)</font>
SB checks, <font color="#CC3333">Hero bets t310</font>, <font color="#CC3333">MP1 raises to t620</font>, MP2 folds, CO folds, Button folds, SB folds, Hero folds.

Final Pot: t1530

[ClockWyze]

What limit? I think that is important here.

[splashpot]

Yea, I think this is fine.