Honestly, If there is no true aggression...I wouldn't be too worried at this point. One will be more dominant than the other. The head thing is typical and just Stig's way of saying "you are mine". Layla does this to her brothers all the time. I wouldnt let it continue with the toys, food or affection though. When he tries to be dominant over objects you need to step in and be the dominant one. They will both respect this. It often takes several weeks for a new dog (especially a bullie) to accept they must share their home. Its all a part of Punkin finding his place in "your pack".