7-3 all-in

[SlyAK]

Gaming Club $5 entry, single table sng, down to 4 players. I am in the SB and am dealt 73o, obviously one of the worst hands in the game. However, blinds get very large at TGC and I have just posted 160 for the SB, leaving me with T620. The BB is third in chips with about T1200 after posting. UTG chip leader approx. T5000 and the Button approx. T2700 fold to me. I think about it for a minute, and push all-in. I have had a tight image at the table, (if anyone at the $5 tables pays attention to other players, which sometimes I think they dont) due to getting very few playable hands. I think the BB will fold if he doesnt have something reasonable, because he doesnt want me to double up, even though stealing his blind will put us close to even.

Anyway, the BB thinks about and as time is running down on the time clock calls w/ T6o. A 3 comes on the flop, and he gets no help, so I double up. I went on to win the tournament. However, how bad is my all-in at this point?? Also, what do you think of his call with T6o???

Thanks for feedback,
Sly