Actually leathers don't need to shed or peel to grow.They do it because many of them,like toadstools are leathery and don't have a slime coat like most soft corals.The only way to remove algae and debris is for them to shed off a layer of film.I say,if it's not looking like it's decaying/decomposing at the base then that is what's going on.I've notice leathers do this more often when there isn't enough indirect flow.They do much better with a strong yet indirect flow,preferably chaotic so the film can get blown off the coral.
A pic is worth a thousand words,can we see what is going on?