Author, author!

My book group meets next week. I chose Here if You Need Me, since I read it recently and really loved it. The book was announced to the group, and then the next thing I know the author is coming to the group! I'm thrilled, except it will be a little weird. What if people don't like the book, but don't feel free to express themselves because the author is there? I also become really shy around people of note, especially ones I really admire. My only hope is to not sound like an ass around her.