Your session has timed out???

Your session has timed out. Just had this pop up on my screen, BUT I am now worried as I was not remotely controlling any other machine at the time, not in a session, and not authorised a session on my system. Had a look in the logs and it does look like an incoming session was started from a machine ID I do not recognise [ID removed]. Not sure if I can post the log excerpt in here but I have saved it. But cannot yet work out if the connection was sucessful or if the message was due to it being refused.