For 4 days they look good to me. I've only grown a couple times. I'm far from knowledgeable. But, my new growth tended to be yellow'ish compared to the darker/deeper green of mature growth.
When you say a "tinge" of yellow, where do you see it? Overall color of new growth, or the edges/tips of existing and new growth?
What soil are you using? It looks like potting mixes which might have nutrients included. Many people report that potting mixes can be too hot for seedlings. Also, it looks a bit shy on perlite. If it doesn't drain well it could look like overwatering.