if the temps regularly go above 85 with the lights on that could be the problem.

if the pot is to large for that plant and the root system doesn't fill the soil then it is possible that 3 days isn't sufficient time to let the soil dry out. my plants don't all take water at the same time.

at 1 month old and only 1 dose of ferts if it was too mild a dose, then you could be seeing the start of difficiencies. also organic ferts don't always contain the trace minerals and other nutes that mj needs to grow. Mg, S, B, Cu, Fe, Mn, Mo, Zn, etc. i use fox farm ferts which contains all trace minerals so i don't have to worry about this but organic growers must be aware of these minerals and how to make sure the plants get them.(epsom salt for Mg, etc.)

now you have to play detective and figure out which it could be, if any. this is the fun part!!!!!

good luck