I was not letting her 'chase me' I know better, please quit treating me like I know nothing about horses. I have been doing ground work. I was not running around like some of you may think, I was walking around, letting her follow me I only said running around to let you know I was moving around...
Breezy, there is no need to get defensive here. You have received some valuable advice, and people have only gone by what you posted originally.
Today when I went out to see her, I was running around, she was following me. Then I ran up to the gate and she ran after me. What concerned me though was when she reared. She lashed out at me. I went to grab her, to put the halter on and she reared again.
This behaviour, as others have explained, is typical yearling play behaviour. You have dealt with her as though you are another yearling to play with.
As cute as it may be, to play with your horse in the paddock, it is very dangerous, even if the horse is not intending to injure you. My own 2 year old still rears and hooks himself over the back of his paddock mates, while biting hard on their necks. I certainly don't want to encourage him to think that he can do the same to me, so since I purchased him as a weanling, he has known that I am nice to be around, but I'm also the boss that he can't play with.