Originally Posted by FBinNY

Odds are that the problem is in the cables, not the pivots. It's unlikely that both pivots would bind evenly so a pivot problem would cause only one arm to bind and the brake to open off center.

Odds are that the cold thickened the grease or other lube in the cables causing the problem. Run a few drops of a temperature stable thin oil, like Mobil 1 into the cable, and work it along the length by working the brakes. You don't have to take the cables apart to do this, simply use the [not so] quick disengage feature to free up some slack and apply the oil at either or both ends of the housing.

BTW- Wind chill doesn't apply to bikes. It applies to expoxed skin, and to a lesser extent to items warmer than ambient temperature.