Villain turned out to have exactly what I thought he had. I debated making another bet on the river but the villain had $70 back and I didn't really want to put $70 more into the pot without being sure my opponent didn't just make his flush.
Am I still playing scared or was this a reasonable check?
PokerStars No-Limit Hold'em, $1.00 BB (9 handed)
UTG ($75.40)
UTG+1 ($30.70)
MP1 ($24)
MP2 ($104.10)
MP3 ($106.60)
CO ($98.05)
Hero ($155.05)
SB ($48.35)
BB ($230.15)
Preflop: Hero is Button with

,

.
UTG calls $1,
1 fold, MP1 calls $1, MP2 calls $1,
2 folds, Hero calls $1, SB completes, BB checks.
Flop: ($6)

,

,
(6 players)
SB checks, BB checks, UTG checks, MP1 checks,
MP2 bets $4, Hero calls $4, SB folds, BB folds, UTG folds, MP1 folds.
Turn: ($14)
(2 players)
MP2 bets $9,
Hero raises to $25, MP2 calls $16.
River: ($64)
(2 players)
MP2 checks, Hero checks.
Final Pot: $64
Results in white below:
MP2 has Jc Qc (two pair, jacks and sixes).
Hero has 6c Tc (three of a kind, sixes).
Outcome: Hero wins $64.