I brewed my first of 2011 today, an AG American Stout. The brewing went fine and I ended up with an OG of 1.060 (shooting for 1.053). I pitched the yeast (US05) at about 80 degrees and went to clean things up. I came back about 15 minutes later and I noticed airlock activity. I figured it was just cooling or something and ignored it. About an hour later I checked again and I definitely have airlock activity - about a bubble every 30 seconds or so. I have had fermentation start quickly before, but never anything like this. Has any one else experienced this or does anyone have a guess as to what else it could be?