Kathy - oddly enough, the "Doonesbury" cartoon has an occasional storyline about students at MIT. Garry Trudeau got a lot of mail after he had a student refer to a 4.0.
He ended up having to explain on the Doonesbury website that, yes, he knew MIT had a 5.0 system, but he knew that a lot of his readers wouldn't know - so he used the 4.0 system.
My guess would be that's why the movie did the same thing.
