Answer: Well obviously there will be a light you would be seeing, and I’m pretty sure the headlight turned on for a reason which is: there might be something in front of the car that the headlight detected. Or the headlight wants to make sure you see where you are going.
Explanation: I did a brain proccess and thought with my head and got this I don’t know what any other reason why a headlight would turn on automatically. I hope this helped :)