I've made three batches with the same colony of WY2112, and each one of them has exhibited the same odd behavior. I pitch a good quantity of yeast into oxygenated wort at 65 degrees F. Within 24 hours I see yeast activity. In a couple more days, the krausen has risen to three or four inches.
At this point I figure I've got a healthy fermentation. However, when I check the gravity after two weeks, I've only achieved around 50% apparent attenuation. Being sure to relax and not panic, I raise the temperature to the mid 70s. Airlock shows increased activity and in another week, the beer is finished at 78% apparent attenuation.
Is this sort of stalled or slowed fermentation typical of 2112?