I don't own a horse but I see them regularly on my walks with or without my dog near where I live. I like horses. A few weeks ago I was walking my dog with my partner. We were crossing a field with horses in it. It is a public footpath. We kept to the edge of the field. We weren't being loud and I thought I was being mindful of not seeming like a threat to the horses. The other horses remained on the other side of the field. Our dog was with us.
We had crossed this field a few times before recently. One of the horses approached us. It sniffed our dog but didn't seem to mind his presence. We didn't have any food with us. It then came up to me and nipped me on the arm. It drew blood but the wound wasn't deep.
Does anyone knowledgeable about horse behaviour know why the horse might have done that? Could it be that the horse was being territorial?