infamous for being hard to get in touch with
I don't think I have EVER gotten a hold of a trainer on the first try. When I was young and DESPERATELY wanting lessons I had to travel quite a distance to get them as there was nothing in my area. I called and called, left messages, wrote letters, etc. Come to think of it I've had the same issue with dog trainers. (especially the good ones! ;) )
I don't think it would be nagging to let her know your new schedule.
The horse, through all its trials, has preserved the sweetness of paradise in its blood. ~Johannes Jensen