In the beginning of the novel before Phillip lost his eyesight he was very judgmental of Timothy based solely on the fact that he was black. He was raised by his mother to think that he was somehow superior to black people because he was white.
After Phillip loses his eyesight he begins to get to know Timothy as a person instead of just as a color and he begins to see Timothy as a friend. Now that Phillip is blind he can begin to let go of the prejudices that sighted people have. When he asked Timothy, "Are you still black?" he is stating how surprised he is by how close they have become. Phillip never dreamed his best friend and protector would be a black man. He never dreamed that his survival would be in the hands of a black man. He is surprised at how much he has changed on the inside in such a short amount of time and it took losing his eyesight to see Timothy for the person he really was.