Title pretty much explains my issue here, but I have a plant of the exact same strain, same age, literally planted in the same minute, but one is experiencing this problem and the other isn't? Raising some alarms in my head, leafs are also curling and drooping but not drying out or showing any signs of deficiencies!
Right now I'm running 6x24w CFL's, soil is miracle gro seed starter (no time release nutes), Horbitec organic soil, and perlite. Strain is Purple OG. May look over watered because I just watered but ill lay off for a few days, perhaps cover with transparent bags so the soil doesn't dry out too quickly because I'm having issues where the soil will dry out every second day!
IMO plants that young still need a cloche. If you dont have one get a sammy bag, prop it up in the middle with a chopstick, and tape it to the cup.
Well the cotyledon leaves are being used up so not long now, but like I said it looks over watered (sick looking uniform yellowing). I think you're probably loving her to death Try letting her dry out completely and watering her with a 1/4 strength nute solution.