Cracks in plastic. Are white IPhones 3G's bad?

A number of iPhone 3G owners are reporting the appearance of hairline cracks in the plastic finish of the phone. According to threads on Mac Rumors forums and Apple’s Discussion Boards, the cracks appear to be manifesting mostly in the white 16GB version of the phone; however, Engadget notes this may be due to the fact that the cracks are easier to see in the white model than the black (see photo below). Importantly, iPhone owners experiencing the issue report that the cracks appear without the device being dropped, sat on, or misused in any way. It is unclear what might be causing the problem, or how widespread the issue is.