Catherine Yes, definitely appropriate. The kiss others mentioned is very quick and chaste; totally okay for kids of that age.
Sarah My daughter,9, and I read this book together. We both enjoyed it and I felt it was appropriate for her age. There was a kiss or two between characters in the book, but it was fine for a 4th grader.
Andrew More or less... If I remember correctly, there is a kiss or two, but nothing too serious, I read it in 3rd Grade, so it should be fine. It's a really good book. Still might be a good idea to preview it though