She does this when I take her halter off when I turn her out, but tonight I just went to check on her and when she was being a little pushy and in my space and told her to back off, she did it then too. I haven't worked her in a week due to the severe ice we have it's not safe to bring her down to the barn.
She just had her teeth done a month ago, seen the vet twice and the chiro once. We've ruled out pain issues, and when she does this I see the other horses do it too. She's turned out with some pretty "wild" horses that are never touched or worked with. I would move her, but until it's safe to move her without falling, it has to wait.
Any insight into this behavior is much appreciated.