Could you take a look at my plant?

From a fellow grower:

It was planted, from seed, in a Rapid Rooter and it’s been about 3 weeks since the seed first touched water. It’s showing a small problem–it looks like either overwatering, too much light, or too much heat (it stays about 80 degrees Fahrenheit in my grow room). I thought it might be too much heat because the oldest leaves are curling downwards, but I am not sure if this is just drooping from overwatering. The nodes are very close together and the plant is growing out instead of up (which is good, I think). I’m using a 300W Mars Hydro light about 15 inches above the plants (real wattage is about 140 watts). The plant is receiving about 30,000 lux of light (as measured at the level of the leaves). I mist the plant with PHed water about once or twice a day, not much–just enough to dampen the top of the soil. Speaking of–I’m using a coco coir/perlite mixture and drainage is excellent. I do a full watering every 3-4 days (water until water starts to drain out of the bottom of the pot) and 1/4 nutrients about every third watering, as well as misting the top of the soil every couple days. My air circulation is good–I have two oscillating fans in my growroom and it isn’t too hot in there.

Am I doing everything right? This is my first grow so I don’t know what to expect. Please let me know if you see any problems with my plant.

PH? what is the ph you are using coco is hydro and should be treated like hydro ph 5.8 ± .3 if you aren’t using this ph then you have first signs of nutrient lockout looks very much like ph fluctuation to me.

Also, it looks like your plant is pretty wet. Overwatering could cause your plant to be stunted in growth. Just my opinion.