Hey Growmie,
When growing autoflowers super soil is never good it seems to be too hot for them, and it ends causing nutrient burn to the young plant, I see it all the time, the good thing is the with a little love and care the plant will be just fine. Just remember with autoflowers since they grow so fast they only require 1/4 of what most nutrient companies recommend, they normally base those charts off of growing photoperiod plants, not autos. Hopefully, I answered your question and remember ..."Happy Growing" and "Free your mind one puff at a time".