[Asterisk-Users] CLI Timeout ?

[Asterisk]

Is there a cli timeout at all ? I normally leave a remote session connected
just to monitor and view what's going on. Yesterday, I went to my console
and found the message

pbx*CLI>
Disconnected from Asterisk server

Now, I thought that may I had restarted the * server from somewhere else and
had forgotten about this old session. 

However, it's happened again today, and I know that I have not restarted *
(well, I did, last night, but started the remote session this morning).

Asterisk -r connects straight back to the cli.

Is there a new timeout (I'm running CVS head as of last night) or is there
something more seriously amiss with this ?

Julian