If I have to be completely honest, while I agree that "keeping checks hidden" would make more sense in terms of realism, I'm sort of glad the game tells you about them, because it gives you some headroom to "cheat" your way around the check, at least knowing it's there. Otherwise too much hidden content would be lost to the player through mere bad luck.
If skill checks had to be completely hidden, then I'd probably also want them as a flat number requirement rather than a roll relying on dumb luck.
