Mystery in my office

I have a pop-up Post-it dispenser in my office. I like it a lot. But I HATE the shock of pulling up that last Post-it and realizing I'm all out. Where's the warning system, Post-it people?

Anyway, I've been aware that my Post-its were getting low. I knew I only had a few left in there. I was prepping myself for pulling the last one. Today, I pulled a Post-it and it resisted coming out of the dispenser. I thought for sure it was the last one, but another one popped up in it's place. Thinking that was weird, I idly pushed on the Post-its to gauge how many more there were.

And it was FULL. And now that I think about it, I used to have green Post-its and these are yellow.

Someone has been in my office. And used my last Post-it. And replaced the pack with a new one.

Weird!