Update
Well, I went out to the barn after work today and tried to put Sunday's experience out of my mind. Gave Rusty a good grooming and just got on with things. No issues at all! He was back to his usual self and we did some transitions (after reading some posts on here, I'm practicing that) and even a wee canter.
I need to remember that he is an animal with feelings, not a machine, and things like high winds may upset him. I can accept that!