Of course its quite normal. Tehre has been no changes... actually 20$ less. Last month was 380 and this month is 360
Well there were some news that for content ads there is flat rates for ads.And in case of google search the biddin will be done.obviously the revenue with search is high. But so far thhe revenues are like same....
I believe it's the summer downtime kicking in right about now, especially if you see a decrease in revenue. If your visitor numbers are the same, but still seeing a decrease... could be the advertisers are not paying as much *right now* or you could of been smart priced.