yellow doesn't mean dying.

as for your plant.. the second they hit the top of dirt they shoudl be in light (if not sooner) ... get it soem light or kill it now before you put work and "love" into it and it dies anyways... =/ btw if it's 4 leaves you might be too late... that means it's went past the bean leaf phase (the first 2 levaes are called bean leaves) i'm just learning about growing, but the things i've just told you know i've learned over 3 years ago now...