Overdue books

Oh, boy! I got an email from our local Library that I have 0verdue books. "What!" was all I can say upon reading the e-mail for it's hard to believe that I missed the due date, never happen before. But when I checked out the printed receipt I got, I saw that I was really wrong and the 8 books that I last borrowed were due for return early last week. I didn't actually realize the due date that was on the receipt until I got the e-mail, because what was registered in my mind was that all books will be due sometime next week. It's strange where did I get the wrong date from. It must be from something that I had read.