Socialize him more with other dogs and if you get a bunch of dogs around you he wont know what to do but be friends. Socialization skills is one of if not the biggest thing these babies need. Maybe enroll him in a puppy class or dog class at Petco or Petsmart? To get Buster socialized I would take him to Lowe's and walk him around the store, there's always dogs there and they would see him and he would see them and it worked out well.
Happy Birthday Angus!!! Many many many more to come!!