Recent update to feed results?

[Matthew Mitsui]

Was there a recent update to the algorithm that ranks the results of the feed API?  Specifically between August 5 21:00 - August 6 1:00 EST?

While I was using the feed API, the results shifted around in ways I didn't expect.  I'm not sure if this is because I was using the same computer (re-ranking results based on history) or because of an algorithm update.  I wasn't logged in to my Google Account and was using the same referrer for all my queries.