I am going away for a few days but before I do I wanted to share with you Googles response to my email. Yesterday I asked is Google ripping me off? and emailed the Adsense Team this is what they said
"Thank you for your email.
I understand that you are concerned about a potential discrepancy between your own website tracking reports and the statistics reported within your AdSense account.
We count impressions only when the AdSense ad code is executed by a user's browser.
Therefore, there are several factors that would cause the impressions you register to differ from the impressions listed in your Google AdSense account.
Instances that wouldn't execute the ad code include: Other spiders, robots, crawlers from other search engines
