I expect that someone got offended by the erotic content once the library had stocked the books, so they decided to remove them. What's the betting that the person who complained made sure they read all three before they reported them?
I bet they did! I'm saddened that the library (of all places!) made the books unavailable. I don't think 50 Shades is particularly good, but I disagree strongly with the idea of banning any book.