Villain is 21/16 over 136 hands. He hasn't showed down before this hand, but he has been aggressive. I thought that even though this was a dry board the river seemed like a possible bluff because there are only a few hands that like the J. Otherwise, he could possibly value bet KQ or AK here... I probably shouldn't have checked the turn though.

PokerStars No-Limit Hold'em, $2 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

SB ($220)
BB ($200)
UTG ($97.85)
MP ($197)
Hero ($280.65)
Button ($188)

Preflop: Hero is CO with A, A.
2 folds, Hero raises to $8, Button calls $8, 2 folds.

Flop: ($19) 3, T, K (2 players)
Hero bets $12, Button calls $12.

Turn: ($43) J (2 players)
Hero checks, Button bets $30, Hero calls $30.

River: ($103) J (2 players)
Hero checks, Button bets $72, Hero calls $72.

Final Pot: $247