You can say what you want about Fox, but the fact remains they as a network do have a track record of breaking big stories, often before anyone else. Even if Politico originally published this, Fox scoops other news networks with a lot of things that turn out to be huge stories, spin or no spin.
However that being said I'm with GrnEyes on this one. This doesn't feel like a cover up. The story doesn't ready like a cover-up (even from Fox there storey420). The article is written pretty blandly and bare bones, except for the R congressman who seems very upset in his quote. They identified a mistake, then corrected it....in JUNE. As far as I'm aware they took no special efforts to bury this event either.