Items Removed Warning?

I get "one item has been removed" pretty well ever time I go to a lot. Every time I go to manage worlds and back I get it. Every time I go to CAS then back, I get it. If I go to CAS, then back, then to CAS, then back, I always get that message pop-up each time.

It must be a programming glitch then because even on an empty lot with nothing at all, I get that message pop up.