What causes powder coating to fail like this?

[Lous69]

Some people were looking at my car this morning and noticed the coating on one of the door handles is all cracked. The other side seems fine, at least so far.

They were both coated at the same time. The car has never seen less than 57 degrees, (the temp I keep my garage at). They were coated about 12 months ago.

Anybody with a lot of powder coat experience know what would cause this kind of failure? It's supposedly clear powder coat on billet aluminum.