yeah wash it gas can eat paint if let soaking in it. i always use a rag on my bike and car incase of it drips never paper towels they can leave fine scratchs in the paint

 

I wouldn't worry about it.

Mine has over-flowed many times over the years when the pump's auto shutoff mechanism didn't work right. After all these years, I have no discoloration on the paint or bumper near the gas cap.