It may be but if you used the same mix for all the plants and no others are showing that it might not be.
They look like normal new growth up top and will darken to the normal green color in a day or two. That plant seems to be producing new growth faster than the others so that’s why it’s showing a lighter green…maybe
Let us know if the new growth doesn’t darken up in a day or two.
Congrats on getting your grow on.
Organic grower here love me some down to earth products.
If you tend to travel for days at a time you might want to look into blumat auto watering or the SIPs pots where there is a reservoir of water at bottom the pots sit on and may work when your away at work.
Here is a thread that might be of interest to you
Enjoy the day