Weird hand

I was playing PLO again. I am in the big blind with QQXY. Flop comes A 4 4. It gets checked around. The turn is a Q. It's checked to me... I bet and get called in one spot. The river is a blank. It's checked to me and I bet; he calls. He flips over A A XY. WTF? Did he think that I had quads? I lost a little tonight, not much (less than $2).