Aww! One of my chicks does that too! She doesn't jump up on my arms like that but she runs to me whenever I go into the run (she's 6 weeks old) and my brother went to feed them for me and he called me and said "one of your chickens is following me around...what does she want?" I just told him to get down on his knees and pet her cause she LOVES that.
I guess that's the difference. I spend a lot of time with them but not tons. I wish I had more time to do that because I would love my birds to love me like that!