It’s got cold and she’s stall bound, there’s your answer as to why....mine is out 24/7 but it was cold the other day when I rode her, and she felt like a bomb ready to go off.
I do not play nice or baby her at all when she is like that, when I can feel her building to one, I make sure to have a short connected rein on the dangerous side, while flexing her gently to the safe side, leg hard in to keep her going into the connected rein. When you get the sudden unexpected ones, shut her down hard and fast, one rein stop, or use both reins....it is unacceptable behaviour and it is fine for you to, in that second, be over hard.
I do not play nice or baby her at all when she is like that, when I can feel her building to one, I make sure to have a short connected rein on the dangerous side, while flexing her gently to the safe side, leg hard in to keep her going into the connected rein. When you get the sudden unexpected ones, shut her down hard and fast, one rein stop, or use both reins....it is unacceptable behaviour and it is fine for you to, in that second, be over hard.