Chrispcritters - 6:09 pm on Oct 2, 2013 (gmt 0)
Unless your main source of traffic is at-work US federal government workers I wouldn't expect to see more than a minor shift in web traffic patterns.
Many businesses run their ad campaigns on a monthly or quarterly basis. I've noted in the past that the first day of a new month often sees a sharp flux in earnings. Even more prominent on the first day of a new quarter. I suppose people are pouring over the previous period's stats to see what, if any, tweaks need to be made for the new period. New rates and new creative can impact performance as a new baseline performance metric (think click through and conversion rates) established by AdWords/AdSense.