Light green mottling in 2 1/2 wk. old plants. WTF?

I have 5 Northern lights plants that are all about 3 weeks old, growing in Ocean Forest with what I think is plenty of light. They are all getting the same nutes, water and light but I noticed that 2 of them have some leaves that are mottled with lighter green. Not all the leaves but enough so that I am concerned. Any ideas guys? Any info would be helpfull. Thanks.

Post a few pictures if possible.

FFOF has more than enough nutes for seedlings that age without adding more.

You shouldn't need any nutes for a month or more.

Wet