2.5 weeks ago, Google pushed out the Penguin 3.0 update after waiting over a year to update Penguin 2.1.
That update later was confirmed and told it would roll out worldwide over the next few weeks. It has been 2 weeks and 4 days and yesterday, Google's John Mueller said as far as he knows, "the whole data is still rolling out slowly."
John said this in a video webmaster hangout on Google+ at 35 seconds into the video. The question was:
Question asked by Baruch, the short version: Is the rollout of Penguin from two weeks ago complete?
John Mueller answered: As far as I know, the whole data is still rolling out slowly. So you might just be seeing fluctuations from that.
Here is the video:
We've seen Penguin fluctuations and still do over the weekend. So this is not surprising.
Forum discussion at Google+.