It was two things:
1) As previously mentioned, CBS wasn't shooting straight down the line of the spot and the camera parallax made the stick look further ahead than it was relative to the ball.
2) The ref (who I think is a rookie) totally botched the signal. Every time I can remember, when a measurement is taken, the ref, immediately after observing the ball, straightens up right there and signals the upcoming down (and if a first down, will give the whole-arm standard first down attained signal).
This ref didn't do that. After making the measurement he makes no signal at all and starts jogging to his position. If you look at the replay you can see during his jog he flashes a "one" with his index finger a couple of times, but he does it right in front of his abdomen. Only when he gets into his position does he give the standard whole-arm first-down signal.