DrDoc - 7:50 pm on Jul 31, 2013 (gmt 0)
Welcome to WebmasterWorld!
While I don't consider myself the right person to help you with the underlying issue, let's see if we can't get someone in here with the right knowledge. Anyone?
Your initial assessment appears plausible. You're saying it appears to be real human traffic? I would say it likely is, then. I mean, you may have benefited from a recent SERP update. Have you changed your site ranking recently?