HUSNG: late into match confused by villains play

[ghettointlectual]

This is the first time villain has done this, he has been limping in all game and has folded or called when I raised his limps before. Is this a trap?

Full Tilt Poker
No Limit Holdem Tournament
Blinds: t40/t80
2 players
Converter

Stack sizes:
SB: t1440
Hero: t1560

Pre-flop: (2 players) Hero is BB with A[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/spade.gif[/img]
SB calls t40 <font color="aaaaaa">(pot was t120)</font>, <font color="#cc0000">Hero raises to t240</font>, <font color="#cc0000">SB raises to t500</font>.