I have my first brew from a kit sitting in my secondary right now. The airlock stopped bubbling for a good 24 hours. I took a final hydrometer reading and everything looked by the numbers. I replaces the airlock to go sanitize my bottling equipment and prepare the primer. When i returnd the airlock is BUBBLING AGAIN. What do you think is going on. I think I'll hold off on bottling untill tomorrow.
I know it was fully sealed because the inner cup of the lock was floating as if there was pressure present but no bubbles.
Did the temperature change at all? That could cause airlock activity. Also, the beer could just be off-gassing. Don't depend on airlock activity as an indicator of active fermentation. You've got a hydrometer, and it sounds like you know how to use it...trust it.