As I was driving up for the Holidays with the temperatures changing overnight from 70 to 40s, I noticed that there was now a 3 inch crack going right from the left edge and then another 3 inches down. I do not recall any collisions that could have caused the crack.

I'm now wondering how that happened, and have two ideas. One, there was a microcrack that was exacerbated by the drop in temperature, or two there was a manufacturing defect. (But good luck proving the latter though) Has anyone faced anything similar? Also, since my xfire is on lease, I'll probably have to replace the windshield now. How much do these cost to replace?

Thanks.