My new sorting horse does this when we let all our horses out in the arena. Not sure if I approve of this yet. He doesn't seem like he's being aggressive to the other horse though. No ears pinned and teeth bared. Just seems like he's playing around, but the other horses don't always enjoy this lol I've also noticed that he's kind of an outsider and enjoys spending more time with me than them. What do you guys think? Good, bad? If it's bad I don't have the first clue how to fix it! Any advice?!?