Party Poker No-Limit Hold'em, $ BB (9 handed) FTR converter on zerodivide.cx

saw flop|saw showdown

Hero ($25)
BB ($15.80)
UTG ($23.20)
UTG+1 ($16.81)
MP1 ($39.85)
MP2 ($38.40)
MP3 ($30.83)
CO ($35.65)
Button ($28.80)

Preflop: Hero is SB with ?, ?. Hero posts a blind of $0.10.
4 folds, MP3 raises to $1, 1 fold, Button calls $1, Hero (poster) calls $0.90, 1 fold.

Flop: ($3.25) 3, K, 2 (3 players)
Hero checks, MP3 checks, Button bets $2, Hero calls $2, MP3 folds.

Turn: ($7.25) K (2 players)
Hero bets $4, ....

What does it look like I have? Why would I check-call the flop and lead the turn?