I made a certain channel for skycraper ads for a small site of mine (I think there are 17 pages). A couple days ago I decided to take all of those ads off. But today I just checked my stats and it says 1 click and 1 impression for that skyscraper channel. I checked each page to make sure it is gone, and it is. If I had accidently assigned the channel to a different ad, there would have been more impressions because I have about 5000 imps per day on that site. So could this have something to do with browser caching or what?
It might have been a user browsing and clicking from a cached page. For example someone visiting your site through google, (typing in cache:www.mysite.com). The visitor might have clicked your previous ads on the cached page, causing it to show up in your stats