Villain stats are scarce with only 7 hands. 71/0. I have one note after 4 hands saying he called down with over cards. I'm not folding KK here, but what's the best line against this guy? His aggression tells me he may have hit a set, since I've only seen him call up to this point. Should I 3bet? What do I do if he 4bets? Is a shove incorrect here?

$0.1/$0.25 No Limit Holdem
7 players
Converted at weaktight.com

Stacks:
UTG ($31.78)
UTG+1 ($40.10)
HERO ($24.65)
CO ($29.05)
BTN ($20.20)
SB ($25.85)
BB ($0.00)

Pre-flop: ($0.35, 7 players)
HERO is dealt
2 folds, HERO raises to $1, CO calls $1, BTN calls $1, 2 folds

Flop: ($3.35, 3 players)
HERO bets $2.50, CO folds, BTN raises to $5, HERO ???