Weird - I have never seen this, and I don't have an adblocker installed, javascript disabled, etc. I wonder if this is geolocation- or browser-specific?
As of last year, it only showed surveys to users from US/UK/Canada. Not sure how much things have changed by now, but it's definitely not global yet. I also heard that it didn't work in Safari, but I'm not sure if that was just a temporary thing.