Dexter loves his obedience class and is doing really well. But at the end of the last 2 classes, when he has 10 mins play time he doesnt play with the other dogs instead he sits and stares at me or the trainer. The other dogs and their owners come up to him to play but he ignores them. It seems he wont leave "working mode". When we go out at the park for fun he loves other dogs and visiting people. But I want him to be able to also have fun in class when he is released. What am I doing wrong? Is he starting to be anti social?