The 'Glassgate' story got rolling with a report in the gdgt newsletter by Ryan Block, who says he spoke with sources inside and outside of Apple about this issue, but was unable to get an official Apple comment.
Block writes: "Apple has apparently found that non-bumper style cases - specifically those that slide on to the iPhone 4, which are occasionally prone to particulate matter getting caught between the rear of the phone and the case - can cause unexpected scratching that could quickly develop into full-on cracking or even much larger fracturing of the entire rear pane of glass.
"To put it another way: Apple is afraid you might buy a standard slide-on iPhone case, put it on your phone, and then discover the next time you take it off that the entire back of your device has been shattered [through] no fault of your own."
Apple is said to be taking it seriously, looking to avoid the sort of backlash it got when reports surfaced over the summer that the iPhone 4's antennas didn't work correctly when users gripped the phones in a certain (and quite natural) way.
Evidence that something might be up surfaced when Apple watchers took notice that the company had suddenly begun offering only its own iPhone cases on its website, not many of the third-party cases that Apple steered users toward in the wake of what became known as 'Antennagate'.