I'm shocked you haven't dented yours.. The first time I went on quack attack after my axle swap, I backed into a rock that pushed the cover into the ring gear, by the end of the day, the ring gear had cut through it and it was bleeding like a stuck pig. I bent it back and welded the hole until my new covers came.
The front was basically same story- I mis-judged a line, and boom, big dent in the cover that was rubbing the ring gear enough to get through.
Maybe the factory covers on jk's are thicker, or maybe it's the fact that I drive like an idiot.