Yes, one gets increased fibroblasts from trauma, such as keloid scars. African Americans and people with allergies are more prone to keloid scars. Since there is repeated trauma from lip biting, it is possible the same thing can happen that happens with keloids when the fibroblasts do not go through programmed cell death or stay there.
A molecular biologist would be best to discuss this theory with instead of a dermatologist since they are trained in this area. You could also copy and paste the post about Random Notes on Fibroblasts/Keloids.