Not only did Kain say little, but he brushed past her rudely and gruffly. He was acting like such a child. And usually, she would have just used this as a golden opportunity to slip back in her room and lock the door - and she almost did. But then she'd never hear the end of it, even if he did deserve it. In those kinds of situations, she never won.
So she followed him, and decided, at this point, that if he could act immature, then so could she. Falling in behind him, she tapped her walking stick forward and caught his left ankle, deliberately attemting to trip him. This would upset him (again, he deserved it), it would distract them from going to the barn, and it would give her some sense of comfort. After all, she'd tried to be civil. And if he landed on his face because of this, she would not feel guilt.
"Oh dear." She quipped flatly as hooked his ankle again.