Cracked windshield @ 800 miles.

Went out to my car this morning and found that it had a large crack across the top. It appears that there may have been an impact at the very top of the glass, very tiny if true, which leads me to believe that a rock may have hit it while I was driving, and then the heat (very hot in NY today) caused the glass to expand and crack.

The car's only at 800 miles. What's the best course of action here?
I assume it's not covered under warranty?

Cracked windshield @ 800 miles.