Ok, so we were doing good until this weekend. My horse is an 18 yr old arabian mare. As far as we know she has not had any formal training. When we go in the round pen I walk next to her for a few laps and she will follow with her head near my waist. She will follow my every move, if I turn she turns, if I stop she stops. Now the problem is lunging starting with the trot. She will eventually get out on the rail with some convincing and sometimes stay at the trot nice and perfect but some times, like this weekend, she would cut in and kind of throw her butt at me and buck. This was not even close to me as I couldn't reach her with my lunge whip. Now I did catch her and do lots and lots of circles until her ears came forward and she was listening to me again. Now by the end of our little session, about 15-20 min, she was back to head near my waist and following my every move. And the rest of the time I was there she was an absolute angel, including taking her dewormer perfectly.
My question with this is what is she doing and why? I understand she is most likely acting out in some way to try to be boss but she starts and ends with what seems to be respect?
I am open to suggestions to help.
Just a side note, we have basically ended her head tossing, she will do one toss just before she's about to act up. She also walks on a lead very well until we get to new scary places then she wants to go home. She is also extremely buddy sour and as the weather improves we will be working on that taking her off property.