[Nexus 4 Q&A, Help & Troubleshooting] cb474:
Just wondering, how warm is your hand in 15 degree weather? Also even if your hand is normal body temperature, would that be sufficient for the whole back, glass and plastic, to heat up much in 15 degree weather? I see why your experience might seem to negate the temperature differential theory, but I wonder if it really is an apples to apples comparison with the Droid Life reviewers experience of putting the phone down inside at normal room temperature onto a stone counterop. Something weird is going on with the glass backs, so I don't think we should quickly rule out idiosyncartic differences in temperature situations. Anyway, more below.

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I get that people are skeptical about the temperature differential theory, as an explanation for how the Droid Life reviewers Nexus 4 and Optimus G glass back cracked when place gently on a stone countertop. And I understand that many people have dropped the Nexus 4 from significant heights (three feet or so), without any apparent damage to the back.

But concluding from this that there is therefore no "serious" problem with the glass back does not make a lot of sense. There are not just a couple but at this point many stories of people having the glass back shatter or crack with very small falls (less than a foot) or just in someone's pocket or being placed on a countertop.

An adequate theory of what's going on with the glass back has to account for BOTH why many phones survive significant falls without any problem AND why some seem to crack with little or even apparently no pressure at all. The cases where the phone falls and is not damaged do not negate the cases where the phone is damaged (from a short fall or less). The sets of different cases together add up to pose a complicated question having to do with the relative durability/fragility of the glass back on the Nexus 4.

So when I put all the evidence together, I don't look at the people's whose phones have survived significant falls and conclude: Oh, I guess there's no problem with the back. Instead, I think: There is something very quirky about this back that makes it often times very durable and sometimes extremely fragile. Either that has to do with intrinsic qualities of the glass itself, with manufacturing defects in some of the glass but not all of it, with the way the glass is attached to the plastic back of the phone, or with manufacturing defects occuring with the assembly of some phones but not others.

This should be a cause for concern with Nexus 4 owners, because there seems to be no guarantee that either 1) you'll get one of the more "durable" Nexus 4s or 2) that a phone which has survived a significant fall won't later break for no obvious reason. It's only been a couple weeks. It will be interesting to see if we get any reports of people who had the phone survive a significant fall only to later have the glass back break for a minor reason.

It is also possible that the people who have dropped the phone and had it be fine have just been lucky. And those with cracks, shattering, and scratches have been unlucky. Maybe in certain circumstances the phone is very durable and in others, if it hits something just right, or has just the right set of temperature circumstances, or some combination of these and other circumstances, the phone cracks extremely easily.

All that to say, I would not be quick to jump to conclusions from any one person's specific experience with the phone. It is all the experiences together that tell the (more real and more complex) story.