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If you are starting a new campaign or your site is listed somewhere and you suddenly get a surge of traffic then adsense will see the number of page impressions rise. They will then see a rise in clicks (hopefully :) ). Provided there is nothing suspicious about the clicks themselves they would assume that you are promoting your website sucessfully. If you get a sudden ctr of 100% because of the new traffic that would ring alarm bells, but if all of the stats are within sensible proportions to each other, but with bigger numbers then nothing to worry about.
Adsense is aware that we all get peaks and troughs is visitor numbers.