ATo on button - Stars turbo nearing bubble time

[cha59]

Big blind's play has seemed reasonable so far - not particularly laggy or tight.

PokerStars No-Limit Hold'em Tourney, Big Blind is t200 (5 handed) converter

MP (t1175)
Hero (t2640)
SB (t3780)
BB (t2385)
UTG (t3520)

Preflop: Hero is Button with A[img]/images/graemlins/diamond.gif[/img], T[img]/images/graemlins/spade.gif[/img].
<font color="#666666">2 folds</font>, <font color="#CC3333">Hero raises to t600</font>, <font color="#666666">1 fold</font>, BB calls t400.

Flop: (t1300) Q[img]/images/graemlins/diamond.gif[/img], 5[img]/images/graemlins/club.gif[/img], 6[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks, <font color="#CC3333">Hero ???