I was lucky the couple of times my T had to change hours on me; one was because she had to take classes and they were only available during my time :-) and the other was because she was giving up one of her offices and "moving back" to 100% in the other. That was a little freaky, having to change offices (a couple hours apart from one another, in opposite directions!) after 6-7 years in one place. We had a lot of grief/conversations about that one :-)