One of my sites were hit on the 28th of September as well. Not an EMD domain so has nothing to do with that.
It was a site that has gained in the search engines every time there's been an big update before from Google. No crappy links, great content.
Mark Cutts confirms there was another update except EMD on this day here: https://twitter.com/mattcutts/status/252484514486575104
However I can't figure out what update this was. Anyone with an idea?