I left a red velvet fridge in the cake overnight by mistake - I only meant to leave it there enough for the crumb coat to harden. Anyhow, I took it out this morning and put the final coat of frosting on. 2 hours later a bubble has developed on the side, and a smaller one on the top. The cake had already settled before the crumb coat was applied. Why does this only happen with cakes I have refridgerated or frozen, and not with room temp cakes? Please explain 











