tedster - 9:46 pm on Oct 14, 2012 (gmt 0)

Yes, October 5 was a Penguin Refresh so it might have impacted anyone, and not just an EMD. The EMD change was on September 28.

However, since it was only a Data Refresh and not an Update (a change to the Penguin Algorithm) it seems to me that it would only impact a site that was previously unaffected if it made significant changers since the last Penguin Data Refresh on May 26.

All these dates and different updates can get confusing I know. That's one reason why we're keeping a master lists for all the big changes we know about - see Monthly Reference - Google Updates and SERP Changes [webmasterworld.com]