TheCount;1894315 said:
That's wierd... they didn't give a ruling on the challenge till after they ruled it a first down.
That's because even if the ball is moved forward, it doesn't mean it's a first down.
Let's say you challenge it, you need a yard, and they move it up a foot. It's considered a "pointless" challenge because all it did was give you about a foot (and no first down), and you would lose the challenge.
That's why they wait to see if it's a first down before deciding whether or not you lose a challenge.