This afternoon, the two GrabPERF Agents at Technorati were switched back to using their local copies of caching BIND for resolving DNS entries.
Some folks at Microsoft who stopped by to look at their results on the Search Performance Index noticed that there were one or two outliers in the results from these locations. When I investigated, the OpenDNS name servers I was using were returning odd results.
The reason I had been using OpenDNS is that the local BIND instances were seeing unusual behavior a few months back. So, consider the switch to the local BIND instances probational, pending ongoing review.
Thanks to Eric Schurman for letting me know.