He'll call pf raises with A3o and c/c A high 3 flush boards. Will also fire random bets. So is this line OK? Is my hand weak enough that I need to protect against a free river card, or should I try to pick off a bluff?

I'm positive my hand is good on the flop, I doubt the K helped. Am I over thinking 50NL?

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

CO ($49)
Button ($37.80)
Hero ($56.40)
BB ($106)
UTG ($117.45)
MP ($51.60)

Preflop: Hero is SB with 8, 8.
UTG calls $0.50, 3 folds, Hero raises to $2.5, 1 fold, UTG calls $2.

Flop: ($5.50) 9, 3, 5 (2 players)
Hero bets $4, UTG calls $4.

Turn: ($13.50) K (2 players)
Hero checks, UTG bets $5, Hero calls $5.

River: ($23.50) J (2 players)
Hero checks, UTG checks.