Any Nexus 4 owners with cracked backs? How bad is the problem?

Forgive me if there's already a post on this topic. I have just received my Nexus 4 a few days ago, and I've been overly careful about how I use the device to not crack the back, so far it's fine. My question is, there were a few stories about cracked Nexii even when not even dropped, apparently warm to cold temperature changes will crack the back right down the center, so does anyone have an experience like this, or is it an overblown problem?