2007 Nissan Altima Hole in compressor

Air Conditioning problem
2007 Nissan Altima 4 cyl 10000 miles

I had my new Nissan into the dealership for an oil change about a month ago. The first time I used the AC after that, Inoticed that it was not blowing cold air. I returned to the dealershp and they told me that I must have run over something like a rock and kicked it up under the car and it put a hole in the compressor. This is not covered under warranty and they want to charge me $680 to fix it. Does this sound like a logical explaination for the hole? I have a suspicion that they accidentally or not so accidentally put the hole in the compressor when I had my oil changed. In either case, do you have any advice for me? Thank you
Michelle