A Mystery Fit For Sherlock Holmes

Joseph: Hey Ed, can I borrow your scissors?
Ed: Sure. [hands over scissors]
Joseph: Thanks. [cuts things]
Joseph: Here you go. [starts to hand scissors back]
Ed: Actually, I think those are yours... See, a while back, a pair of scissors mysteriously appeared in my apartment. The day after that, a pair of scissors mysteriously disappeared from my desk. There might be a correlation between those events and a potential third event, wherein a pair of scissors mysteriously disappeared from your desk and appeared on my desk.