My stripe snow has done it twice in two years. The picture below was taken after she got out of brumation, she had done it sometime during brumation, but I couldn't pinpoint why. Then I found out how she got the scab when I witnessed her doing it to herself during her restlessness while she was very gravid... about a week before she laid her clutch. She was "digging" under her water bowl, looking for a place to hide her eggs I suppose.
So that's a good possibility on your's too, if she's had any kind of structure that's sort of heavy in her enclosure that she might try to dig under.