0.50 NL- 4 Bet Jacks Out of the Blind

[Osprey]

I just started playing 6-max NL, transitioning from so-so results at full ring-
I've been playing 20/ 13/ 2.5 and generally don't get out of line.
Villain is about 16/14/4.75- seems rather nitty. Over 650 hands.
Should the 4 bet have been bigger or not at all?

Poker Stars, $0.25/$0.50 NL Hold'em Cash Game, 5 Players
LeggoPoker.com - Hand History Converter

BTN: $41.20
SB: $20.30
Hero (BB): $102.65
UTG: $13
CO: $48.85

Pre-Flop: J[img]/images/graemlins/club.gif[/img] J[img]/images/graemlins/heart.gif[/img] dealt to Hero (BB)
<font color="red">UTG raises to $1</font>, <font color="red">CO raises to $4</font>, 2 folds, <font color="red">Hero raises to $9</font>, UTG calls $8, CO calls $5

Flop: ($27.25) 3[img]/images/graemlins/diamond.gif[/img] 5[img]/images/graemlins/spade.gif[/img] 9[img]/images/graemlins/club.gif[/img] (3 Players)
<font color="red">Hero bets $18</font>, UTG calls $4 and is All-In, <font color="red">CO raises to $39.85 and is All-In</font>, Hero folds