I would try another vet first.
Our first vet was in beautiful office, large clean and so nice looking. the vet gave us some ok information but my wife was upset that alot of the paperwork they gave us looked like it was printed from an undesirable website.
For $10 they would cut the nails, so since we were new and still struggling with cutting nails we asked them to cut the nails, we could watch and learn. the vet and helper had NO idea what to do, they couldn't control the glider and couldn't get the nails cut, we started worrying they would cut the nails to short, so we asked them to stop, my wife and I could do a better job then that and we were bad at nail cutting.
we found a new vet, father and son with glider experienced, they seemed to have much better knowledge, and skills at just handling gliders. stuff like pulled out a fish tank, put our new unbonded glider in it and then could look over the glider threw the glass without getting bit.
I have not heard or seen this issue, most self mutilation I have heard is over grooming of fur not nails.
If I had no clear direction, I would ask the vet to do a stool check.
I would use a wet towel and just clean his feet, nothing else since bathing a glider is bad, but I would atleast clean off his feet the best I could. I would get him a clean new sleeping pouch and wipe down the cage bars with the water/vinegar mix my wife makes. Also consider in a day or two cleaning any toys and stuff inside his cage, dawn dish soap and water.