It may be the pan. Are you using metal?
My sister used to bake all her cakes, she makes cakes for a living out of her house, in metal until she started notices things like that. She now will only use glass for specialty cakes, such as carrot cakes. She will only use the metal when she is doing the molded cakes like character b-day cakes and only uses regular cake recipes.
I don't know, just adding what I know my sis has gone through. I always ask her advise when it comes to cakes since she's been making and decorating cakes for 12 years now.