That is funny. Maybe, Mark wants to see you during the day and he purposely leaves things behind. That would be really cute if that was his reasons behind it.
Honestly, I have locked my keys in my car twice and had to call my dad to unlock it. After it happened the second time he had another set made for me so I would always have a backup set. The only problem is that I didn't have a key to the house on the spare set. I have also lost my keys and just couldn't find them for a couple hours only to figure out they were still in the lock on the door