I saw a "Free" book on iBooks today and decided to download it. I've never used iBooks before.
After it downloaded (and I entered my password), I clicked "Read", and iBooks said:
Computer authorization was successful.
You have authorized 2 computers out of your available 5.
I only have one Mac here. (iBooks seems to be new with OS X 10.9, and this is the only Mac I've ever owned that is even capable of running 10.9.) Is it including my old iPod Touch as a "computer"? If not, how can I figure out what the other "authorized computer" is?