Should I have reraised his raise on the flop? Anything wrong with how I played this? I didn't want to scare him out of the hand but I wanted to get all his money by the river.

PokerStars No-Limit Hold'em, $0.10 BB (8 handed) converter

SB ($9.90)
BB ($3.10)
UTG ($3.35)
UTG+1 ($1.40)
Hero ($10.45)
MP2 ($4.15)
CO ($4.10)
Button ($11.05)

Preflop: Hero is MP1 with 9, 9.
2 folds, Hero calls $0.10, 1 fold, CO calls $0.10, Button raises to $0.7, 2 folds, Hero calls $0.60, CO folds.

Flop: ($1.65) 3, J, 9 (2 players)
Hero bets $1, Button raises to $4, Hero calls $3.

Turn: ($9.65) Q (2 players)
Hero bets $4, Button raises to $6.35, Hero calls $1.75 (All-In).

River: ($21.75) 7 (2 players, 1 all-in)

Final Pot: $21.75
Main Pot: $21.15, between Hero and Button.
Pot 2: $0.60, returned to Button.