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I can confirm that the site did NOT receive triple the average number of impressions according to analytics, a popular tracking service I use and my own host stats so it is an adsense reporting problem.
Google really could be doing a better job of keeping its publishers informed as to (a) what it's doing, and (b) how it will affect them.
I am all with you, but why would Google want to do that? If you were such a dominating service (to avoid the word monopoly) would you share information? Would you like transparency? I surely wouldn't want my "publishers" to know anything at all. I'd say, "crank out pages, that's what you shall do, not question what I am doing."