Didn't the Bears line move further Bears right before the game? And now it's happening again?
My guess would be they're moving to the other team as the bets are coming in against the Packers and so they're just balancing it out. As scores aren't nessarily to get the score correct, but to balance the bets, if the bets are balanced, in theory the books (at least as I understand it, and just to be clear, I might know nothing about gambling) but my understanding if the bets are balanced, then the bookers win no matter which team wins.
As far as what moved the line, the only official items that I know of, are the Packers coverage ILB got cleared from concussion, and the Falcons coverage ILB got a concussion and was then ruled out for the game. But those would of moved the line the other way.
Also they say Slit film turf is the worst, currently used by Vikings, Saints, Colts and Bengals. The Lions, Giants and Jets recently got rid of it, for new "improved" turf, though some looking at Rodgers injury might disagree.
I believe the Giants/Jets got the same stuff that the Falcons have.
Other than that, the only other noteworthy thing is OT Bakhtiari is calling out the NFL and very specifically called out Roger Goodell, so conspiracy theories would be suggesting the refs will screw the Packers (especially if it's the Packers offensive), as Bakhtiari is calling out the boss.