Hi BJ
If you are still wondering about you "yeasty" buttermilk starter moz - I don't know if you are aware that you can expect a yeasty smell on other cheeses (I get it after 3 days on a drying reblochon, but I don't see bubbles as it is a semi-hard by that stage). I doubt it will be dangerous, though you may not intend to repeat the buttermilk experiment. But since my moz is sometimes slimy and I'm not dead yet, I venture to guess that some bacteria (gas producing ones) get over productive when you left the milk, I think that a similar problem arises when I don't stir my moz enough (at the curd in whey stage). Still since my sterilization protocol is pretty strict except for using good raw milk, I think the bacteria should be friendly ones.. I hope
Regards
Alison