The iPhone 4’s “death grip” antenna issue has been well-documented on the pages of Consumerist and our sister publication Consumer Reports. But now comes news of a possible second design flaw, already dubbed “GlassGate” by some, in which slide-on iPhone 4 cases are reported to have a shattering effect on the device’s rear glass covering.

Here is how one GDGT reporter described the problem:

According to my sources both inside and outside Apple, after Antennagate the iPhone engineering team identified another potential design flaw that appears to have sent them into a quiet lockdown, and has them working behind the scenes in what’s been described to me as something of a quiet panic to preempt any further tarnishing the iPhone brand. Apple has apparently found that non-bumper style cases — specifically those that slide onto 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 by no fault of your own.

The GDGT story goes on to claim that Apple blocked “nearly all third-party” cases for the iPhone 4 from being sold in its stores, and that Apple staffers were hard at work investigating the problem.

Consumerist has yet to notice any reader complaints about scratched or shattered glass from slide-on iPhone 4 cases. If you’ve experienced this problem, please send us a message at the tipline.

With Antennagate over, is Glassgate next for the iPhone 4? [GDGT.com]

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.