Key from derek@xxxxxxxxxxxxx changed?

While pulling the latest changes from the venge.net/off.net
repository, I got this:
 
 | [...]
 | monotone: connecting to venge.net
 | monotone: [bytes in: 564] [bytes out: 733] 
 | monotone: warning: key 'derek@xxxxxxxxxxxxx' is not equal to
 |         key 'derek@xxxxxxxxxxxxx' in database
 | monotone: [bytes in: 612] [bytes out: 770] 
 | monotone: read from fd 7 (peer venge.net) closed OK after goodbye

What does this mean? How do I handle this "key change"?

Peter