Congratulations! My best with AdSense has been around $4 -- most are less than 20 cents. I remember when "mesothelioma" was the keyword everybody and his brother was shooting for, because some of the advertisers (law firms mostly) were bidding $50 or more per click. As a result, sites related to mesothelioma (I think it's a lung disease resulting from asbestos exposure of something) were springing up all over the place. Not sure what happened with that trend. Probably a lot of those sites are long-gone. But anyway, $20 earnings for 1 click is impressive. I'm still hazy on your calling it an "impression," though. How do you get $$$ for AdSense impressions?
Impressions doesn't pay you much in Adsense. Surely this would be a bug and your earning might be withheld when the month final calculation is done at the end of the month.