In Google Adsense there is an ad unit that is showing as Active, even though I am sure it's not on any of my pages. I checked the ID against my entire website folder with
grep and nothing came up.
Under "Performance Reports" the ad unit appears to get an average of 4 impressions each day. Where might these ads be showing up? From a (really) old cache, perhaps? Is there any way to find out exactly what pages gave those ad impressions?