2003 paint chiping

Yesterday I stoped by a local car wash to knock some bugs off the front of my car. I put the sprayer on rinse and started using it on the front of my car when all of a sudden it knocked a 2" x 3" chip of paint off my hood. I wash my car weekly and some times twice a week. I try my best to take care of my vehical. I never drive it in the rain and won't drive it much of the winter because of the gravels and salt they put on the road. I don't understand what could have caused this. Did the sprayer have to much pressure? Could there have been a mark there where a gravel could have hit my hood and the sprayer finished knocking it off? Is the paint on my model car prone to doing this?

Anyways know i'm considering repainting the hood. How much should it cause to paint my hood back to stock black?

Thanks,