It was just a placeholder. Drudge, like most untrained, uninformed, unchecked blog-drool pundits of all sides, has about as much credibility as a mumbling bearded guy with a shopping-cart full of doll heads who lives under a bridge.
From CNN: "A portion of the switcher experienced a momentary glitch. The "X," was in fact a place-marker for the CNN logo, which was being cued for transition. It was for operator use, and never meant to go on air."
I use a lot a lot of the same software they do. And yeah, it happens! An unrendered logo will be replaced by whatever placeholder symbol your software uses for that. In this case, the 'X'.