I threw that is just because I can't discount it. Can't find up to date usage stats but there was a slight seasonal increase in September (Comscore reported 3.1% increase in minutes) due to college kids returning to school.
The increase from Google I'm seeing on this site is much more than that, almost 20% starting this past Monday and sustained through the week. (The traffic for this site usually runs in a very narrow range day-to-day making it very easy to pick out anything abnormal.) And the increases from other SEs are negligible, 2% to 3% for MSN, AJ, etc., so for this site it isn't a user search increase across the board.
I know the terms the site should be starting to get extra hits for as we run up to the holiday season starting with Halloween next week, on to Thanksgiving and through Christmas. So far these terms are each at levels I expect -- fractions of a percent.
Of course, a .05% or .1% increase over many, many, many different keyphrases can easily account for the increase and won't register on my preferred keyword tracking tool, my eyeballs.
Still think it might be somewhat Google-related and, in light of trillianjedi's observation, at least enough to keep an eyeball on.
<added>Of course, there are always combinations of factors that happen to coincide and make it impossible to put your finger on the deciding one.</added>