Breaking Bad Alchemy re-downloads on iPad

I bought the Breaking Bad Alchemy book which is over a Gig download. I sync'd it to my iPad and it took quite a while, as one would expect for such a large file. Once I open iBooks on the iPad and select Alchemy, it starts downloading it again - apparantley the full Gig-worth, too. What is going on? I have pretty severe monthly download caps and don't need to download this thing twice.