An AppleDefects reader sent us the above picture of his white MacBook, with the case cracking much in the same fashion as others that we have reported on. Here’s the story that was attached to the image:

I received this macbook last fall. The first one had so many problems it had to be replaced. This crack only appeared few days ago

Are the MacBook cases slowly degenerating or are the cracks the result of something else, such as poor plastic quality or even abuse?