I noticed they're all getting a bit more yellow than green...do you think I need to do something? I've been watering them every 2 days
I'd make sure you're temps stay below 80ish if you can, and maybe move the light a little further away until they get a bit bigger and form a nice root system, then you can move them super close. The seedlings I had were not liking the light so close so I raised them about 6" away from the tops of the seedlings and they looked a lot better. Watering every 2 days might be too much. Only water when the top 1" or so of soil is dry (be careful not to damage any surface roots when poking your finger in), overwatering starves the plant of oxygen and stunts root growth. Best thing to do is water very good then let dry out for 3-4 days max then water good again. If you dry the pots out nice they'll love it, just try to keep the rH (humidity) up in the room if you can. At this stage it's hard for them to drink so keeping the rH up helps keep it hydrated. But don't mist the plants tho, if you're rH is too low, below 25-30% just buy a cheap 'cool mist - vaporless' humidifier. I had one running 2hrs on 30mins off for 3 weeks then I just returned it to the store hahaha.... If you don't want to spend the money there's other ways like putting a cookie sheet pan in the grow room, (or even a wet towel) and putting a thin layer of water on it and have good air circulation. It's not going to push the rH up too much but any little bit helps.
Also you may want to invest in a digital pH meter for like $15. Get the probe kind, not the test strips. Then, when you water, you test the pH of the water run-off that drains from the bottom. Watering with distilled water also helps keep pH stable.
That's my advice and other than that, they look great =] Hope this helps!!