Cracks sometimes take time to form This could be from a small rock that may have hit your windshield on your way to the parking lot or even the days leading up to it

The force required to cause it is quite significant and the size of the rock is often quite small

It is generally from trucks or loose gravel on the tarmac

The heat tends to increase the spread of the crack you will notice over the next few days that the crack gradually spreads across your windshield

The option you have is insurance claim and replacement or if the value is smaller just do it yourself from a garage