Audio problem: When Kevin is going through Buzz's private things he finds a picture of his girlfriend. Sickened by her appearance, he smashes the picture. But the smashing sound starts before he hits it. (00:22:05)
Audio problem: When Kate is riding in the truck with the Kenosha Kickers playing "Deck the Halls", drums are heard. When the drums are not heard, the drummer is still seen drumming.
Answer: Because he's understandably angry that Kevin's so unreasonably scared of him and assumes the worst in him without even getting a chance to know him. He never gets a chance to talk to him, because he always runs away too quickly. The first time he gives him that stare was when Kevin was watching him shovel from the window. Nobody would like to be stared at like that while doing a simple task.
MikeH