Leaves curling inward

So I am growing 12 plants, 12/12FS. I noticed last week that one of the larger plants was starting to have its leaves curl in, and that it was mostly the new growth. Thought maybe the fan was hitting it a little hard or maybe it was a little to hot/humid in the tent that day because sometimes things are not as controlled as I would prefer. Anyways, I pulled the problem plant out of that tent along with 2 other plants because they were 5-6 in. taller than the rest and was not helping my canopy out like that so I thought this might also help with the leaf curling. It did not, that was 4 days ago and it has only gotten worse. I do not think it is ph or nutrient related as I have dealt with that before. I have this feeling it is root bound, I just find that hard to believe since it is in a 2 gal. nursery pot and only 12/12 FS and have seen people pull the whole shebang off in that size container with more veg time than I had. But it is also the biggest plant of the bunch and the only one showing these symptoms. Now that I have explained the situation, here is some pics of the plant. It is about 10 days since it started budding, 15 since first pistils so I am weary to transplant because I do not want to stress her out but it would be worse imo to try and finish her in to small of a container. Let me know if you think I am on the right trail with the root bound diagnosis, and feel free to ask for more info if you think it will help.
Master Kush Day 33 from germination

just a touch to much nutrients. I wouldnt worry about it man. Plants look healthy. Dont change the pot unless your already watering her to often like every day or every other day.

K I will back off the nutes for a sec, thought she would be a little darker if it was toxicity but she doesn't look hungry at the same time so no harm in giving her sec to do her own thing. Oh and they only usually drink twice a week, one of those is feed which is Canna Terra.

id just back off nutes by alittle like if you were feeding 700 ppm id go 500 ppm. Ive seen the leaf thing on your girl many times(more on sativas) and I just back off a feeding or 2 and by then the buds are filling in so there ready to be fed full strength again.

I have 8 plants in 5 gal. lowes buckets the tallest is 18 inches and I havnt watered in two going on three weeks, whats going on there????
two 400 watt MH in a 3x6 foot area, the soil isnt drying,70-75 degrees and45% humidity.its Time to go 12/12 but I want to switch to Big Bud but soil is still wet,dry on the very top, fans going I even drilled holes in the side of the pots at diverent heights thru out the pot. Ill get some pics tomorrow.

how much are you watering when you water them? No drainage in the bottom? what kind of medium, assuming dirt but what kind? Something is definitely wrong there, but you plants look okay for not having been watered for 2 weeks?