The plants look like they are suffering from air that is too dry and too warm. 80'F is not outrageous, but you have to make sure that you are watering enough. Don't DROWN the plants, but they do need more water.
I'm a little worried about your soil only because that MG organic has fertilizer in it already from the factory, and small seedlings don't want ferts for the first couple weeks of life.
Next time your soil looks dry, and it looks dry in the pics as I recall, check that your pots have a lot of good drainage and give the plants a gentle but heavy watering so that some water comes out the holes. Hopefully it will take some of the excess fertilizer with it.