Quite honestly, would you really expect the government to publicize bonafide evidence of alien civilizations that it found?
they don't even tell us about possibly dangerous approaching asteroids/close calls until after they've already passed and the threat is gone. I highly doubt they would tell us anything about alien civilizations or alien contact if it were made (and would probably only try to use such knowledge for their own military advancement). scary stuff our government.
what, me, worry?