I see this from time to time as well. Here's another example:
Oct 17 23:02:44.000 [notice] Our IP Address has changed from 52.64.142.121 to [CORRECT IP]; rebuilding descriptor (source: 86.59.21.38).
52.64.142.121 appears to be an instance on Amazon's EC2. I don't run any nodes on EC2. 86.59.21.38 resolves to
tor.noreply.org.
I'm unable to find any occurrences of this happening from Faravahar, however the issue seems to be fairly common. What's going on?
We've had one suggestion so far:
That the iptables forwarding rule from Faravahar's old address might not be preserving the original source address.
Another possibility is that authorities running directory caching proxies are re-using the X-Your-IP-Address-Is header meant for other clients, rather than generating it fresh for every client.
A third possibility is a bug in the tor authority code, which sets X-Your-IP-Address-Is to the wrong IP.
Tim