I've been having an issue with the ad all day. It's called Scorecard Research.
It's not too intrusive but it shows up very frequently even if I click the link to opt out of it. I've cleared my cache and tried a different browser and still have the same issue. I can see it wreaking havoc if someone is accessing the site via a phone or tablet and not using the app. Some of those pop over ads are pretty hard to get rid of on small touch screens.
The kicker is that I run Ad Block Plus (long time user) and it got past that.
Like I said it's not a huge deal but it will get annoying if it continues.