Rivering trips w top kicker in small Pot and getting raised

Hand converted with online PokerStrategy.com hand converter:

Play hand

$0.01/$0.02 No-Limit Hold'em (4 handed)

Known players:
[tg]BB$3.78:///////;CO$5.00:///////;BU$5.35:///////;SB (Hero)$14.47:///////;[/tg]

Preflop: Hero is SB with A:s, 2:s.
CO posts deadblind, CO checks, BU calls $0.02, Hero raises to $0.14, BB folds, CO calls $0.12, BU calls $0.12.

Flop: ($0.44) 7:d, 2:c, K:c (3 players)
Hero checks, CO checks, BU checks.

Turn: ($0.44) 5:c (3 players)
Hero checks, CO checks, BU checks.

River: ($0.44) 2:h (3 players)
Hero bets $0.46, CO raises to $2.00, BU folds, Hero folds, CO gets uncalled bet back.

Final Pot: $0.9.

Ok this fold seems not right with hindsight, does it? I mean, what can he have?