Gas cap tank left open; car wash

My girlfriend took my car to the gas station to fill it up as a surprise for me. After that, she decided to do something nice and ran it through one of those touchless car washes. She drove about 50 km running errands before heading home. When she got back, I noticed the fuel door was still open and the gas cap was hanging loose. I’m worried that water may have gotten into the fuel system. She said the car drove completely fine on the way home.

What should I do?