I live in Winnipeg where its -40 regularly during the winter. No cracks on my phone. Ive had it exposed to the air to. I dont think warm or cold really has an effect, I honestly think its manufacturing defects. We know we have screen issues already...
you're failing to see the point in this
gorilla glass is manufactured by replacing smaller sodium ions with larger potassium ions, so in lesser space a larger ion has to fill the spot the sodium ion once filled, this creates a pressure that pushes the glass together and rids of "imperfections" on the glass
now on to the hot and cold part
you ever wonder why the electricity lines are tight in the winter and loose in the summer? same logic here..
what happens is that if your phone screen gets to a certain temperature and is heated suddenly, the material wont have enough time to adopt to the new temperature, and since heat causes expansion, the potassium ions would create a even larger pressure and pushes the glass apart
jusy my 2 cents, since gorilla glass i created by dipping glass in 400C molten salts, id assume only the surface is "gorilla'd", which is the reason why only a side of it would crack
edit:
the screen defect is not related to this at all
the screen defect is caused by the circuit behind the screen not being able to provide equal power to all parts of the screen, it has nothing to do with the glass
now this is rarely an issue on LCDs, but amoleds consists of numerous of oleds per pixel, so each of them is powered and signaled through some sort of controls, some of these oleds dont get enough currents, which is why this issue exists