Yes, I think it should have been added it, because at the scene in the office in the movie, the audience doesn't know why he doesn't want to go to biology class, unless they've read the book, and they have to listen carefully to the movie, just to be sure it's that scene. :)
i was really looking フォワード, 前進, 楽しみにして to this moment in the movie it shows so much of the chemisty between edward and bella ....not having it makes the movie lacking