if it comes back to you, it's yours?

[lotsofplants]

This was amusing. I'm at a friend's house, and glancing at their bookcase, and I see a book that looks really familiar.

"Huh" I say, taking it down. "I didn't realize you had this book".
*flip through*
*notice my name in the front cover*
"Um, is this my book?"
"oh, yeah. I should probably give that back to you."

I had kind of wondered why I hadn't seen it since I moved out. I'd just assumed it ended up in one of the boxes of books...