Straight draw OOP - line check

I only had 30 hands on villain, but he had been pretty loose pre-flop (43/8).

Party Poker No-Limit Hold'em, $ BB (10 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

UTG+2 ($34.80)
MP1 ($54.93)
MP2 ($26.65)
MP3 ($52.75)
Hero ($66.55)
Button ($110.09)
SB ($42.44)
BB ($15.06)
UTG ($17.23)
UTG+1 ($60.32)

Preflop: Hero is CO with T, 9. SB posts a blind of $0.25.
6 folds, Hero raises to $2, Button calls $2, 1 fold, BB calls $1.50.

Flop: ($6.25) 5, 7, 8 (3 players)
BB checks, Hero bets $4, Button calls $4, BB folds.

Turn: ($14.25) Q (2 players)
Hero bets $10, Button calls $10.

River: ($34.25) 2 (2 players)
Hero checks, Button checks.

Well I think you ran into a call station. He most likely he had a pair of 7s or 8s, but there is a small possibility that he had an OESD with a 6.

Good river check against this type of player, if they are calling down that far, they are going to call a river bet.