You're not the only one experiencing that problem. I am too. I called iBook support and they have a ticket open about the issue. This didn't happen for me until I updated to the latest version of pages.
I'll call them tomorrow and point out that you have the same issue.
THANK YOU FOR POSTING!!!!!
I'm also here searching for an answer to this exact issue. Sorry I can't be helpful, but I'm posting here in hopes someone with a solution will take notice and help us out!
MacBook Pro 2009
OS X 10.7.4
Pages 09 4.2 from Apple App Store
iBooks 2 (2.1.1)
iOS 5.1.1 (iPhone 4s, iPad 2)
I also didn't have this issue until I updated to the most recent version of Pages from the app store.