Here's the link to check:
http://www.goodreads.com/rescue_books/at_risk
Even if you checked before, check again! As of Wednesday, I had no books to rescue. As of yesterday, I had three - all Kindle books. I checked again today and there were two more. Again, Kindle versions. The issue appears to be mainly with ebooks with no paperback versions.
Sure, you can manually add the books later, but if you don't know the title and author and didn't write a detailed review, how will you know what book to add? I'm not sure what data they CAN keep.