So i have had this imperial stout sitting in primary for about a month, transfered it about 2 weeks ago to secondary ontop of some carraway seed and cocoa nibs, just today the airlock started bubbling again and it looks like the top of the beer has a dark brown layer of krausen on it? i took numerous readings on this thing and came to the conclusion the fermentation stopped a long time ago, now i am just letting it sit to get some more flavor. Anyone know why it is bubbling again? could it be a possible infection?