Party Poker No-Limit Hold'em, $ Hero (5 handed) converter

UTG ($2818.50)
MP ($1222.08)
Button ($2067)
SB ($1741.59)
Hero ($1158)

Preflop: Hero is BB with Js, Jc. SB posts a blind of $5.
1 fold, MP calls $10, Button calls $10, SB (poster) completes, Hero raises to $55, MP calls $55, Button folds, SB calls $55.

Flop: ($205) 4h, 7h, 3c (3 players)
SB checks, Hero bets $180, MP folds, SB calls $180.

Turn: ($565) 2s (2 players)
SB checks, Hero bets $350, SB calls $1496.59 (All-In), Hero folds.

Final Pot: $2411.59



Ok, this would seem like an easy fold normally, however because of such a dangerous flop, I was really surprised to get raised on the turn. The only hand I could really think that he would do this with is a strait, which still seems very bad not to raise the flop on.

Based on that, how often do you think when an unknown does this, they are a bad player with a slowplayed set, or a tricky player with a flush/combo draw? Vs. most regulars I would be much more inclined to call here, but since he was an unknown i just decided to fold.