8 days old, yellow leaf

my plant is growing well for 8 days old, but this morning i seen a leaf is starting to turn yellow.

my light is not touching the plant and i have not started to feed it any nutes yet.

the temp has been between 75-82 all the time. 45-60% humidity.

is this going to be a problem because it so soon? any advice?

Put it under the sun and add magnesium when you feed it

take it out from under the light to put it under the sun? what dose that do?