I used to breed gargoyle geckos. No I never saw that.
There are 2 possibilities I think.
1) Your gecko has had and/or now has MBD (calcium deficiency caused by improper diet). If he has eaten the rapashy diet his whole life, that is very unlikely. If not, and if you are switching to the diet, and he is healthy enough to eat, this should correct the problem over time. It will not, however, be enough to erase the deformity. It will simply stop the problem from becoming worse and strengthen the bones as they are.
2) Your gecko has a birth defect. Nothing you can do in that case.