I had the exact same thing happen, but I actually saw the rock hit. The crack developed over time, it was below where it could be visible from inside for a few weeks before finally becoming visible. It's about 3/4 of the way across my windshield, 6 1/2 years later.
Worth a try since there's no indication of a rock hit. I know my dealership wouldn't do it, they tried to claim my whole electrical system was off warranty because I'd replaced the stereo in the car, and that my drivetrain warranty would be gone if I did aftermarket shocks and springs.