This thread is a crack up. I saved it this morning to read later thinking it was going to be something juicy, another 'shoes in the house' thread perhaps. Pffft!! Pretend it didn't happen and if she says something say you've never noticed it before. Surely somebody's shoes/heels could do that? I actually noticed a mark in the tile in the first photo, but not where you say it is. Up in the top left by the bottom of the cupboard. What's that?
And I'm sorry, but those tiles are not rare!!!