KKxx in $5 PLO

[Blindcurve]

PokerStars (9 handed) FTR converter on zerodivide.cx

Blinds are 15/30, all raises are pot sized

Preflop: Hero is UTG with K[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/diamond.gif[/img], 4[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/diamond.gif[/img]. SB posts a blind of 15.
Hero calls, UTG+1 calls, <font color="#666666">3 folds</font>, CO calls, <font color="#CC3333">Button raises</font>, <font color="#666666">2 folds</font>, Hero calls, <font color="#CC3333">UTG+1 raises</font>, CO folds, Button calls, Hero ???

Neither of these players has done anything egregious; I am very concerned UTG+1 has AAxx. Given that, what's the correct play?

-D