You ask WHY? and it's a big question.
It would need an expert in Teflon coating techniques to offer an answer. It could be one of...
Inferior raw material
Poor manufacturing process
User error
But knowing why will not help your current situation.
Your options are to continue to use it if you can or to invest in a new one.
Presumably a warranty claim is not possible for you?
Good Luck..., August 2016
