Oh dear, sounds like you've had some real negative reactions to saying something like this before...but really really really nothing at all wrong with what you said. Like other posters said, it's a fact, and it will help the librarian to hone in on the right books faster, which should be his/her goal.
I hope they really were pleasant, sometimes body language can make all the difference in whether I end up regretting having said something...
(At least you manage to get your books back on time!! That is forever my source of red-cheeks.
)
