I would say it's bubbling,
because you moved the fermenter.
Usually the most LOGICAL answer is usually the correct one.
You're thinking in terms of bubbling = fermentation.... Think of an airlock as it's supposed to be thought of, as a VENT a VALVE to release gas, NOT as a fermentation gauge. All that more than likely happened is gas that has been present ALL THE TIME in solution got released, either from it being trapped in the yeast at the bottom of the vessel, because of some physical shaking of the vessel or the room it is being stored in, or the change in barometric pressure putting pressure on the liquid in the vessel or a rise in ambient temp causing the co2 to expand beyond the layer that was in the headspace. Or opening the fermenter to take a gravity reading....
Or because they moved the fermenter.
Airlocks bubble for many reasons Barometric changes/Temp changes/ A truck rumbling by on the street/The cat brushing against it/Vacuum Cleaner....Bubbling of an airlock, especially if it's been idle for awhile, is usually a product of changes in the environment, rather than anything else.
Or because they moved the fermenter. (Are you detecting a theme here?)
That's what so many brewers into trouble, they keep thinking an airlock is a fermentation gauge, that any time it acts up or doesn't act up they think fermentation is or isn't occurring. If you think of it as it's REAL purpose, as a release valve to keep the beer off the ceiling, then you realize that you dealing with gas which is fluid in it's own right, it expands, contracts, and comes out of solutions form many reasons beyond JUST fermenting....
In your case the answer is obvious....
Yesterday, 3 weeks after brew day I put my 6 gal carboy with IPA in the kegerator next to a keg.
I highly doubt that you managed to levitate it without shaking it around. You kicked up the co2 that was in there.....Relax
