<VV> Powdercoating problem related to age

[scmills]

Got a wierd situation. My spare tire wheel (which has never been on the 
ground) was sandblasted and powdercoated white several years ago (3?).

I notice yesterday that the powder paint has cracked all over. Looks like 
cracked glass... It has gotten alot of sun but no more than the other 4 
wheels.

Anyone got any explainations? I glanced at the other wheels which were done at 
the same time and they still look great.

Thanks!

Chris