It might be due to what a couple of people have already mentioned: you're height makes it so that you have to squat lower. Combine that with staying pretty upright during the motion and you probably recruit your glutes a lot. Or it could be that your glutes are the limiting factor in the lift; in other words, your back/lower back is stronger (proportionately for the lift) than your glutes so your glutes give out first.
Maybe, as its been mentioned, try rack deadlifts, or even try doing them without going all the way down.