Some of them seem juvenile, but the fact that your reading habits can be monitored without court proceedings is something that every library user should be aware of.
I never would have assumed they couldn't. By a snooping librarian, even if not by the FBI.
I don't think it's likely that a librarian would bother to look through my very boring records, but it's certainly no less likely than the prospect of an FBI agent doing so.
I don't know how many librarians you know, but the ones I know zealously guard the privacy of their patrons. They take that custodial duty extremely seriously. Librarians as a group are some of the staunchest civil rights advocates you will find anywhere.