A childhood belief about mirrors

I read a funny comic about a nerd boy and a talking cat with loads of magic machines. In one chapter the boy fell in love with a popular girl. He went and visit her but she wasn't there, so he stayed in her room and waited and while waiting he used a magic cloth to wipe the mirror in the room, and what happens is the magic cloth makes the mirror show the reflection of people who used the mirror before and you can see what they did, like looking at themselves. The boy saw the girl naked in the mirror. I still think if I look at myself naked in the mirror someone else would wipe it with the magic cloth and see me naked and I feel scared whenever I get change in front of a mirror.