Am I reading her the wrong way???

Is it illegal or, well, just impolite to borrow a lot of books from the library? I mean, I really want to know what the protocol is on this particular matter. Because I seem to be having an issue with my local librarian. Here's the deal: each time we go to the library (which is about once every 10 days or so), we rent at least 10 or 15 books and magazines. Today, I ran over to the library by myself while my mom watched Zeke so that I could return some things and borrow a stack of magazines for a long plane trip we're about to take. Well, as I set the large stack on the counter and said "hi!", Ms. Mean Librarian Lady sighed and scanned my library card - WHICH DIDN'T CONTAIN ANY OVERDUE FEES!!!! She acted as if I were taking her own private stash of reading material from her own home! Is it not my tax dollars that pay for my local library services??? Am I not entitled to borrow as many books as I'd like??? Is there a law on the "books" about some type of limit that I'm not aware of??? Fill me in if you know something I don't. Because as for me, I'm gettin' the vibe that Ms. Mean Librarian Lady is p.o.'d that I have the April edition of Martha Stewart Living on loan. Whatevs.