yeah I thought that, and maybe accidentally got stuck to the page, but then she told me she'd found several.

perhaps someone just liked their bookshelf to look haunted?

oooooh....that is a thought -might have been a prop in someone's (?lockdown) video?  The local TV/film industry regularly shops for props in this store and sometimes donate right back when they're done ...perhaps the amateurs have cottoned on....

Weird one...

Two ideas, both film related. First, it's a pretty classic film trope to open a mystical book and have it glow on your face, and this would be a quick and dirty way to achieve that special effect. But the fact that they're a bunch of normal books and not big elaborate leather-bound things makes that questionable. But second, if your lighting is cheap and only from a few sources, a book can throw an undesirable shadow over an actor's face. Putting a tiny light inside to throw a little upward at them could balance that out, and in that case it would need to be on a variety of books, whatever random thing the actor in the scene is supposed to be reading.