NL25 - Do you ever fold this on river?

[Jw513]

Villain is 36/16/1.3 in about 30 hands. So not too big a sample yet.

Full Tilt No-Limit Hold'em, $0.25 BB (6 handed) Full Tilt Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

BB ($48.65)
UTG ($40.60)
MP ($63.65)
CO ($23)
Hero ($28.10)
SB ($29.50)

Preflop: Hero is Button with 9, Q.
3 folds</font>, Hero raises to $0.85</font>, SB calls $0.75, 1 fold</font>.

Flop: ($1.95) 3, K, 3 (2 players)</font>
SB checks, Hero bets $1.5</font>, SB calls $1.50.

Turn: ($4.95) J (2 players)</font>
SB checks, Hero checks.

River: ($4.95) T (2 players)</font>
SB checks, Hero bets $3.25</font>, SB raises to $10</font>, Hero calls $6.75.

Final Pot: $24.95

I hit low straight on river, but backdoor flush hits also. Villain checks for the 3rd time. I bet and he raises. Now I'm like 90% sure this is some type of bluff. I don't think a king raises for value on the river here. I also rule out KK/JJ/1010 because no 3bet preflop.

Hows my line? Is this always a call a here? .. since we beat villain's range most of the time. I really think this is a bluff or a weird value raise with K10/KJ.