What's wrong with this leaf?

I have 3 plants and two are healthy but one of them has yellow lower fan leafs. Plant is 5 weeks old from seed.
I'm thinking it may be overwatered?
Thoughts?

Here is better pic, as you can see its the middle plant

You have to explain everything about your environment. Then I can look at the leaf and tell you what's wrong with it. What are your parameters of growth. Lights nutes humidity temp. Growing medium etc. Nitrogen deficiency for sure tho.

Mister Pickles said:

View attachment 5155095

Click to expand...

Could be the water or it likes more nutes then the others or has less in the soil. That looks like one of the older leaves from when it was younger. They kill those off as they get older to recycle the nutes. Probably you flushed your nutes out in the run off.. top dress or add liquid nutes especially nitrogen.

ICGA said:

Could be the water or it likes more nutes then the others or has less in the soil. That looks like one of the older leaves from when it was younger. They kill those off as they get older to recycle the nutes. Probably you flushed your nutes out in the run off.. top dress or add liquid nutes especially nitrogen.

Click to expand...

I think you could be right. I've given it some nutes this morning as I think its just hungry, This will be its first feed. Thanks for help

Lower leaves will sometimes die off like that as they are no longer needed by the plant. Those look healthy I wouldn't stress it. Pluck & proceed.

On a second glance, the lower leaves yellowing can be a sign of Nitrogen deficiency. It tends to start bottom up, lower leaves will yellow/brown and fall off or look like your first picture.

Thanks Calvin.
I normally get yellowing near the end of flower but this was going yellow 3 weeks from seed. The others seem totally fine and they are all the same strain (skunk#1) which is very resilient strain.
I gave them some feed yesterday so hopefully it doesn't spread. I'm guessing it was hungry as the whole plant looks a lighter green than the others?