A. Yes! That is fine, there was likely a fluctuation in temperature and it caused the culture to sink. It can sink, it can float on top or sit in the middle-- it's fermenting all the same. Your culture is still working hard to produce a new culture that will cover the surface of your brew. Evidence of this new culture should appear by Day 7. It can take up to 2 weeks for a new culture to grow in on the top.