I don't know, Sesame.. if he's normally responsive, then I can't help but wonder if he's got some kind of personal crisis going on. Even with a family emergency or whatever, it seems that a therapist would make some kind of arrangement to let clients know, even if it's just on their voice mail greeting.

However, if he was, say, in an auto accident and is not able to speak, or is in a coma etc., then he really would have no way of responding as he normally does. If he had a partner in practice, or a receptionist, then they would be able to handle it.

Let us know what you found out!