Feedback needed...

I am currently in the FBI pre employment process and just took my polygraph 6 days ago.  The result from the polygrapher (Federal Agent) whom administered the polygraph was that I passed. He also pointed out that he does hundreds of polygraphs a year and that he grades them very strictly. Presently, I just got a call today and got a heads up from a friend of mine in the FBI, that FBI headquarters said I failed my polygraph due to using countermeasures during control questions.  I am very pissed off and frustrated because I don't even know how to do any of these countermeasures.  Until today, I had no idea there ever was a way to use countermeasures during a polygraph. All I know is that I was extremely nervous through the entire process and I answered all the relevant questions fine.  If the agent who gave me the test said I passed, do you think I have a direct argument that I can take back to human resources?  Please help!  I just don't understand how the U.S government can wrongfully accuse me of something this absurd....

YOUR OPINIONS OR PROFESSIONAL ADVICE WOULD GREATLY BE APPRECIATED...  THANKS