This one is just weird and I thought I'd share it for the "ohmahgawd nooo stuck ferm" crowd.
I made a Maibock of OG 1.080 on June 26th and planned to ale-ferment it because it's too warm even in my basement for lagering during the summer. I used a 2.5 liter starter of Wyeast 1338 European Ale to do the dirty work.
I had a really active fermentation and a lot of blowoff that lasted five or so days. Temps held steady at 70F, the very top of the range for that yeast. After 10 days or so it was completely stopped, a nice cake had formed, and the temp had dropped to 68F. I took a gravity reading and was sad to see 1.040.
I didn't really have a backup plan for that one, as I had no more yeast on hand, and thought about the best way to restart it. However, my brewing schedule looked tight at best--I was working all week, had company staying in my home, and was going camping over the weekend. I just left the carboy alone, now in my living room from gravity sampling, for another week.
Today, 2.5 weeks after brewing that batch, I checked on a red ale I made about 10 days ago and saw that it was definitely finished and so brought it up stairs. I remembered my Maibock and thought, "Oh, I wonder if I could wash the yeast from the red for this." But just as I thought that, I noticed the airlock on my Maibock bubble. Huh?
I looked under the carboy cover and sure enough it was active fermenting again, visibly churning and generating a few inches of krausen. The temp was all the way up at 74
1338--the amazing disappearing, reappearing yeast!
So there you go, worriers about stuck ferms. Just slosh your carboy around a little bit, let it warm up and you will probably solve your problem, maybe accidentally.
I almost hope that the batch turns out below average so I don't have to try to duplicate this fermentation. Hrmmmm...