While this might only affect a small number of people, the cracks all appear to be hairline cracks in the exact same location, and appear to differ only in length. There's is no indication whatsoever of an impact in any picture. That hints of a manufacturing defect (or a design defect, heaven forbid), and Apple should probably be covering these under warranty. However, Apple is digging their heels in and saying that this is user-caused damage, and so the user must pay for any repairs (a $300 deductible, in the case of Applecare+, $800 without).
Had Apple not done that, this would be a complete non-story.