Leaves curling downward, just the strain or something more???

I'm growing 4 seedlings right now, all bag seed from three different bags, and one of them is looking a little odd. Its leaves are curling downward, which I know is a bad sign, but I'm treating it the same as the other three babies and they're doing great. This particular little one did have some problems with being fed nutes at too early an age(see my other thread, droopy leaves), but now there is new growth and it is a much healthier color... here's some pics tell me what you think. I'll also post pics of the healthy looking ones for comparison purposes, maybe its just going to be like that from the early damage? Just one of the quality's of this mystery strain maybe???

ur probably over watering it.....i have the same size cup and i just put water in until it drips from bottom... i pour maybe 2-3oz in a 18oz cup

id agree overwatering is so easy in soil. wait till the top inch of soil is dry b4 watering and try to get an idea of wen needs watering by weight of pots gd luck!

i used to wait until i saw my leafs droop, but I go by weights of the pots....after a few watering i can usually gauge where the moisture is.

Well thanks for the replies, but I don't think I'm over-watering. I do water them thoroughly but only about every other day. Plus there is one more seedling in the same size container one week younger and it is doing great. I water them till the soil is moist and not again till I can see(the containers are clear, obviously) and feel(by weight of the container, as you mentioned) that the soil is near dry. Mystery I guess...

The first pic in the dixie cup looks like you might have over nuted just a wee bit.
Leaves will curl at the very end if you have given to much fert. They don't look all that bad though.