If an MMS agent is killed or restarted, there is a five minute timeout when it comes back online before data is sent to the central MMS servers. This time is used to see if there are other agents available and the central MMS servers hold an election to see which agent should be primary.

This is touched on briefly here, but needs to be more prominent:

http://mms.10gen.com/help/single/#using-ssl-with-mms