I noticed it last year. At one of my last library performances of the summer, a mother sat in the front row with her kids and recorded much of my performance on her cell phone. I really don't mind people taking a few pictures, but I'm not wild about bootlegged versions of my shows, either sound or video. I've just begun asking the librarians who introduce me to ask that nobody record without my permission.
That's a standard part of the introduction of storytellers at big festivals. Weird to have it reach down to local libraries.