Opponent is 12.8/2.8 over about 300 hands

Full Tilt No-Limit Hold'em, $0.50 BB (9 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

saw flop|saw showdown

MP2 ($10)
Hero ($96.05)
CO ($37.20)
Button ($67.65)
SB ($44.65)
BB ($10)
UTG ($96.80)
UTG+1 ($93.30)
MP1 ($50)

Preflop: Hero is MP3 with A, A. UTG posts a blind of $0.50.
2 folds, Hero raises to $2, 2 folds, SB calls $1.75, UTG (poster) raises to $6, Hero raises to $16, 1 fold, UTG calls $8.50.

Flop: ($32.50) A, Q, 8 (4 players)
UTG checks, Hero bets $21, UTG calls $21.

Turn: ($74.50) 6 (4 players)
UTG checks, Hero checks.

River: ($74.50) 7 (4 players)
UTG bets $24, Hero ????

Only hands I am worrying about here really given the preflop action is K K and K A so the question is do they scare me enough not to call this flop given I checked behind on the turn looking to see a board-pair?