yellow seedlings (pictures included)

hi all,
i've searched around on this forum and others, and google
but i haven't really found an answer that helps with this
problem. what's happening is, right now i've got 3 seedlings
growing in the same grow space under 90 watts of cfls
with a fan blowing over them softly. all are potted in
premium potmate potting mix and i haven't fed them
nutrients as i think they're too young (2.5 weeks from
seed). out of the 3 seedlings, one of them has yellow leaves
all except for the first set of true leaves.

i'm not sure if it is a nitrogen deficiency because they are
only seedlings and i'm not sure if it's a problem caused by
temperature changes from cold to warm, cold nights
and warm days as shown in this link near the bottom of the
page: International Cannagraphic Magazine Forums - The Complete guide to Sick Plants,pH, and Pest troubles!
because only 1 seedling looks like this, not all. so it can't really be
temperature seeing as only 1 is affected in the same space.

here are some pictures to help you out with helping me out:
(sorry if the pictures aren't that good, i took them with my
nokia 6120)

bump.
any help at all would be greatly appreciated,
it's only a baby!

does the soil mix you are using have nuts in it? if youve gotten 3 weeks without any nuts in the soil, I would go with def. givem a little nuts and water and see what happens. Lighter color is not always bad. All plants grow differently, just watchem. I am using a soilless promix with no nuts in soil and i started the first week with like 1/8 nuts and mine never burnt now on week 3 im giving full doeses and i think they can handle it more. If you work your plants into it slowly they can take on alot their weeds after all.

yeah, the soil i have has some slow release nutrients in it.
i've applied half strength charlie carp twice so we'll see how it
goes. thanks for the reply. i'll update you on the situation