What happened to the door and key?

When I got home for winter break I pulled out the keys to my apartment from my pocket. It's two on a chain: one for the front door and one for the mailbox. I felt something strange and I scrutinized my hand. I remembered the front door key was engraved with my apartment number but when I read it, it was a random string. Then I looked at the mailbox key and it was just a different key from what I remembered.

Later during that break, I went to lock the door and the mechanism appeared off. For this, I remembered the mechanism would go parallel to the floor when locked but instead, it remained slightly upturned.

It's a bit foolish to obsess over it.