When I make a starter I usually place 3.3 Oz of Briess golden light DME in a 2 liter flask and let it boil for one minute than cool to 80F. This usually takes about an hour. I then place it in a 1 liter flask, add some yeast nutrient and place it on a stir plate. I have been using a stir plate for about 1.5 years and probably made 14ish beers using the yeast made this way. The last two times I have made a starter; within 24 hrs some of it has foamed out of the flask. From what I am reading this is not an issue but I am curious if anyone knows why, all of the sudden, this started to happen? I used some yeast I never used with a stir plate before. WLP320 and WLP570. I don't believe I every had this problem with my go to yeast WLP001 or WLP005.