My T has always told me why she has to cancel. I guess I don't know that I feel like she owes me an explanation, but I appreciate knowing the reason because I would feel uneasy and maybe a bit worried if she didn't (is she okay? are her kids okay? is this going to be an ongoing thing or a one-off?, etc). Sometimes she calls to cancel and spends 10-15 minutes checking in with me if I have the time; other times she just cancels via email.