Last Wednesday or late Tuesday night, October 16th or October 17th, Google may have pushed out a Panda refresh. If so, this would be Panda update number 21.
Update: Google implied that there was no update around this time frame.
The ongoing WebmasterWorld thread has an uptick in Google webmaster communication on October 17th. One said, "My spidey sense tells me something rolled through at some point yesterday(16th)."
Also, a reader sent me some charts showing a Panda recovery on several of his web sites. He actually sent me several and they all seem to show the same pattern. 
They all had very little traffic and then several jumped up on October 16/17th.
The only monitoring service that shows a major change around those dates is SERPmetrics, but MOZcast and SERPS.com do not show major changes:
The previous Google Panda update was on September 27th, version #20. So time-wise, it is possible there was an update.
I will reach out for Google for confirmation on these rumors.
Forum discussion at WebmasterWorld.
