I suppose villain had either an overpair or a set, but the bet is a strange size (and a check might be more profitable than his donk. This suggests to me that the better does not want to see a bet). Any ideas?
Hand converted with online PokerStrategy.com hand converter:
$0.01/$0.02 No-Limit Hold'em (8 handed)
Known players:
[tg]BB$2.77:///////;UTG2$1.48:///////;MP1$4.97:///////;MP2$0.29:///////;MP3$1.77:///////;CO (Hero)$2.84:///////;BU$0.77:///////;SB$0.98:///////;[/tg]
Preflop: Hero is CO with A:d, K:c.
2 folds, MP2 raises to $0.06, MP3 folds, Hero raises to $0.18, 3 folds, MP2 calls $0.12.
Flop: ($0.39) 9:d, 3:s, 7:h (2 players)
MP2 bets $0.11, Hero folds, MP2 gets uncalled bet back.
Final Pot: $0.39.