Explain what happens at the end of Chapter 28. Why is this significant?

Father Gaston Leboutilier visits Saul while he is playing on the road. He tells Saul how poud he is of him. Saul is happy to see him but their is an undertone of tension. It is the last time that Saul will see Father Gaston Leboutilier but his shadow will reach into the end of the book. Will will learn the tragic connection between the two later in the book.