She is now in surroundings she is not familiar with. The ear pinning may have more to do with that, warning you to stay clear. When she does this, move her hindquarters every time. Direction doesn't matter, sideways, backwards, enough to make her uncomfortable. Usually a light repititious tapping on the chest will move her back or by pointing a whip, maybe even lightly tapping will get her moving her butt sideways (laterally). This asserts your authority. If you trail ride with another she will likely be fine. Horses don't usually try to cut until directed to do so.