I had one or maybe two times when I came into his office at my session time but there were previous client and T asked me to wait a little bit like 5 minutes... He never goes out of the office to say hello to client, he waits there so if its my time I come in except if he goes somewhere else and sees me he says hi and ask me to wait a lil bit
I think if client goes away at 5.00 and your session is at 5.00 then it would be difficult for a T to start conversation to other client after few seconds but I think he simply went to bathroom.