4 weeks from seed, stunted growth and yellowing lower leaves

Hey all, I've been lurking for a while and thought I'd post as I'm in need of some help! My Ghost Train Haze #1 popped about four and a half weeks ago. It was transplanted from a small seedling container to a 1 gallon smartpot about six days ago when it was moved from a heating pad under a two light t8 fixture to my veg tent under a gavita pro 270 lep.
Since then it seems that the lower leaves have been drooping, turning yellow, and ultimately crisping up and dying. The top of the plant looks okay so far, but it seems like growth has either been stunted severely or stopped completely.
When I first noticed I considered the plant might be too far from the light and boosted it up a bit with an empty container though that didn't seem to help.
I tried to be careful not to overwater though it is a possibility. I haven't fed with any additional nutrients, and have used Roots Organic soil the duration of this plants life. Though I've never had issues with this soil, could this possibly be an N or Mag deficiency? My temps also swing a bit, going as low as 66 and as high as 80 sometimes, though they are usually right around the 75 range.
I've uploaded the pics to show exactly how its looking. If anyone has any suggestions or ideas as to what this could be any help would be greatly appreciated!

they lose those lower leaves no worry, getting them evenly watered is important so don't let the top soil dry out because there are roots just below the surface and if they dry out they die.

Thanks for the quick reply!
My topsoil is a bad indication of moisture in the soil because of my humidity, generally 20-25% RH this time of year so it dries quickly but my root ball is fairly dense and about the size of my fist, filled the original container completely before transplanting.
The yellowing seems to be staying on the spear leaves and not progressing upwards yet, and when I watered last night I fed with 1/4 strength of some Roots Organic veg nutes just in case of an early deficiency.
My main concern though is the complete lack of any growth. Does transplant shock typically last longer than a week? I'm thinking it might possibly be root bound too but I'd imagine the transplant would have helped address that.
I'm just hoping she doesn't die early, I've got only got one more bean of the ghost train and was pretty excited to try it

when watering those grow bags make sure there is no space between the soil and bag or the water runs down the side. when you water start at the outside edge get it moit first then do the inside make sure they get wet all the way to the bottom. If the soil isn't evenly moist the roots won't grow into the soil. when pete moss dries out it's hard to get wet again so keep it moist use a spray bottle. 25% humidity is low. my go to for sickly plants is worm castings tea with some kelp extract, fulvic acid and a little molasses.

Thanks for the help! I'll try the tea next watering and see if there's any improvement. I usually water the whole way through until I get a bit of runoff, but as for the topsoil I'll have to start spraying or possibly look into getting a humidifier for that room.