Sorry If this is a dumb question.. Is it right that Google are banning webmasters from adsense who use Adsense on Proxy sites??? Maybe I should just go read the TOS...
Actually I believe that Google has something in their TOS that says you can't use it on the header of a proxy site program. I think it's related to the fact that people could use your proxy program to view adult sites, and google is big time no-no against adult sites. Was the adsense on the main page or on the leaderboard?
As long as it's on NON-PROXIFIED pages you are OK... but make sure you have content... something describing what a proxy is for example.