Is this a problem? How to fix? :( **please read**

Day 16 marijuana plant(kaya gold).
yellowing of new nodes and leaves what's this? How to fix? Is it overwatering underwatering?

Some times the new growth will be a lighter color and darken up as it grows I don't think that plant looks old enough to have a nute deficiency just keep a eye on it and if it continues to yellow give it a very light feeding as that is a small plant and will probably burn easily.

Dont the cotyledons have enough to provide for the seedling? Like slim said, new growth can be lighter than normal and everything still be cool...I wouldnt worry if I was you!