I brewed a black IPA last Sunday using a 2L yeast starter, which is what I usually pitch (I tend to brew big beers). Typically I get a vigorous fermentation with very short lag time and I usually get a blowoff. This time I pitched at a cooler temp than usual (I brewed at a friend's house on his rig) and there was a longer lag time, but the airlock got bubbling pretty good by Sunday night. Over the next three days the airlock bubbled steadily (about once every 1 or 2 secs) and never threatened to blowoff. Last night I came home and the airlock was totally clogged and yeasty gunk had seeped out of the carboy around the stopper. It looked like a blowoff, but when I attached a bowoff hose it hardly bubbled (my expereience is that during a blowoff, fermentation is vigorous and a lot of CO2 is being produced). Also, the foam quickly receded. After cleaning up, I reattached the airlock and it continued to bubble about every 4 to 5 seconds. What's going on? Has anyone ever seen this occur - and is it a sign of a contamination? Why would fermentation just move along steadily for days and then suddenly go crazy? I haven't checked on it yet today but am a little anxious to see what shape it's in. I'll post again after I do that.