After looking myself, it is indeed the uptime module loading the server module.
At time of press, the uptime.mod in 1.6.7 had no real documentation, which has been rectified for 1.6.8 (which, if all goes to plan, will be available on Jan 1st 2002).
The uptime site, has the job of tracking servers, as well as uptime, and as such, requires a server name to be sent. Hence, if your bot is a limbo bot (the eggdrop name for NON_IRC_BOT), then you can't use the uptime.mod
Slennox noted the lack of docs for the uptime.mod when he annouced the release of 1.6.7, and produced a small page, discribing it;s purpose and so on, you can read it
Here