Concerns about lower leaves

How concerned should I be about some dying leaves that are low on the plant? I think either due to no light from the new ones blocking them or perhaps something else.

How old are the plants?

It depends on "how" they are dying, and like dirty asked -- how old? Also, is it all of the lower leaves or just one set? When plants go into flower the fan leaves will typically turn yellow and look like they are dying due to the plant sending all of the energy to the buds, but you could be talking about anything at this point.

Thanks I will try to get pictures up.

They're probably about just under 3.5 weeks old now. They are real short but have tons of leaves. maybe only about 5'' tall maximum but full. I just started to add nutrients with a high Nitrogen rating. Trying to keep the amount of nutrients low as I know its easy to over do it. It appears that a couple of the lower leaves are curling over and becoming dried out at the very bottom of it.