I believe yellow seedling is a ph problem.
That makes sense. I spritzed the soil a little as the sprout was bending out of the soil with water I had ph-ed previously. I double checked last night and the water in my spray bottle had gone a tad acidic. When they all got a watering the other night I used freshly adjusted aerated water. I hope she greens up with the new water in the next couple days. It sounds like I'm overwatering but I'm pretty stingy as a rule of thumb, they're all on the moist to dry side of things.
Thanks a lot, good to have something concrete as a basis for the future.