After my last brew(beginning of may)I harvested the yeast cake(slurry) to 3 glass jars, put them in the fridge to store them for my next brew(11. June 2016). I'm about to make a starter to get the yeast count up, and hopefully use it in my brew.
A couple of hours before I started to boil the DME wort, I took one of the yeast jars out of the fridge to get the temperature of the yeast up(to not shock the yeast). After a 1/2 hour I noticed the jar was under severe pressure, and the lid was about to pop. When I slowly opened the jar, the yeast was percolate out.
I'm wondering if my yeast has gone bad or if harvested yeast normally builds pressure when in exposed to warmer temperatures(room temp.)? I know the "old" Whitelabs yeast tubes had a little pressure when they were warmed(room temp) up, but noting like the yeast I harvested last month.¨