Day 3 of fermenting -- activity has dropped, small amount of foam on one side of the carboy and none on the other side. Looks like some yeast just sitting on the top of the juice. Should I be concerned about any of this? Temp was a little low in the low 60's so I bumped it up a few degrees in the last 24 hours and activity initially raised but has seemed to slow again. Temp is now 68. Yeast is Danstar Windsor.