Is anyone else using Google Experiments with Marketo on their home page? If so, are you noticing that it is redirecting externally referred page visits which Marketo then records as having originally came from the home page instead of the external site?
Visitor clicks on organic Google link so original referrer should be "www.google.com/..."
But the visitor is redirected causing first visit to record in Marketo with referrer url = "www.yourhomepage.com" and query parameter containing something like "utm_expid=3545964-24&utm_referrer=http://www.google.com/url?...."
Thus original referrer is incorrectly recorded as "www.yourhomepage.com" instead of "www.google.com/..."