AJ- standard, but somehow strange spot

[murmeltier21]

Hey guys!
Villain is 21/0 over 30hands. He seems to play kinda dumb poker, but I haven't seen him take this line before.
I really wanna raise this [censored] up like I usually do, but with these stack sizes it's kinda weird.
What do you think?

Party Poker, $0.50/$1 NL Hold'em Cash Game, 5 Players
LegoPoker Hand History Converter

BB: $175.66
UTG: $314.79
CO: $223.51
Hero (BTN): $161.03
SB: $66.94

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

Flop: ($11.50) K[img]/images/graemlins/heart.gif[/img] 7[img]/images/graemlins/diamond.gif[/img] J[img]/images/graemlins/club.gif[/img] (2 Players)
<font color="red">UTG bets $10</font>, Hero?