Rules question from Pack/Bears game re: replay challenge

[SossMan]

Al started to get into it, but I missed his explanation about why the packers didn't get their timeout back after challenging the spot.

The way I understood it was that if you challenge the spot and they move the ball, you won the challenge. Down/distance shouldn't matter, right?

Can someone explain this one to me?

In case you missed it, there was a 3rd down play where the Chicago RB was tackled right at the 1st down marker. They measured and he got it by a foot or so. GB challenged the spot and the ref moved it back by about a foot. They remeasured and it was still a first down by the tiniest of margins (the ref nearly had to get on a knee to see).

GB lost a timeout even though they "won" the challenge.