The early reaction to the Nexus 6P from both critics and owners has been mostly positive, but a few new owners seem to be encountering serious problems. Specifically, the glass panel on the rear of the phone, which covers the camera, LED flash, and laser autofocus module, is reportedly cracking and breaking on its own. A user on the Android subreddit reported the rear panel cracking, and at least two others have corroborated with similar stories, with the panel splitting into multiple cracks with no particular rough handling or impact.
image credit: top - Reddit user Backglasscrack123, left - jonny_rat, right - freshprinceofsf
Note the lack of a distinct impact mark and relatively even cracks along the rear glass. In addition, an Android Police reader wrote in to say that his Nexus 6P's front glass panel cracked when he took an airline flight. He also told us that Google has referred him to Huawei to address the problem.
This Twitter user is reporting a similar experience, though he doesn't include a photo.
@GoogleUK Hi! Wanted to raise an issue: I've just had the back panel of a new Nexus 6P crack while it was sat (untouched!) on a table..
— egg of a black goat (@steamyhams) November 7, 2015
Of course without being present at the time of the damage we can't say definitively that all of these cracks are spontaneous, but multiple reports of similar behavior is distressing. As you might know, metal is much more prone to expand and contract along with changes in temperature, humidity, and air pressure than plastic. So it would make sense that the 6P with its all-metal body (a first for the Nexus line) would crack more than other phones. Creating a phone with a metal body requires tolerances to be built in at the engineering level - note that similar designs from HTC aren't known to be especially likely to crack without an impact.
The good news is that any glass panels that crack as a result of a design flaw should be covered under the standard hardware warranty, and should be eligible for free repair or replacement, since all Nexus 6P phones currently in owners' hands are well within the warranty period. The bad news is that owners may have a hard time convincing Google Store or Huawei representatives that the cracked glass isn't the result of rough handling or impacts.
If the front or rear glass on your Nexus 6P has cracked seemingly on its own, leave a comment on this story or the original Reddit post, then leave another one on the Google hardware forum. If this is indeed a widespread problem, the more people that make their displeasure publicly known, the morel likely owners are to get quick and easy warranty service.