I have a quick question regarding bull calf behavior. Whenever I go in this pen with this guy I get the feeling like he is not happy with me in there. He is a 6 month old, probably around 300 lb guernsey, not fixed yet. Today when I went in the pen he was following me around, he would go and run really fast around me and then return to following me. I pulled him away by the collar and he thrashed his head up at my arm to make me let go. He also nudges me with his head on my leg or something. Is this just playing or is he being aggressive?