i agree with THG, there are a few possibilities here, an auto strain, mistaking slim sword looking blades poping up from branch joints as pistils, or the least likely, since your lights are on 24/0, due to having the warm "flower spectrum" bulbs in there it could be flowering due to maturity, again least likely cuz of light schedule and the size of the plant, when i was growing with LEDs my plants started to preflower more then most peoples plants before the 12/12 flip, i would guess the boost in flowering although on 24/0 was due to the LED fixtures having 2 veg spectrums and 2 flower spectrums, as well as 3 others for balance and fungi control. but all in all id be leaning towards the first 2 options, either its an auto and you didnt realize it, or your mistaking typical node growth as preflowers, the little slim sword like blades are for protection, it helps to protect the fresh new preflowers before flowering growth starts, both males and females have these little sword like blades in the crotches of branches, you wont start to see even preflowering unless you force flower by flipping to 12/12 or have them veg for months, under my 4ft 4bulb HO T5 lights it took about 3 months of vegging for it to start preflowering on its own after its had alternating nodes for a while.
sorry for the run on, nice friday with a whole lotta nothing to do, already been toke-n lol
also again what THG said build up that enclosure around the plants, your just losing valuable light energy out into your room, bounce that back at the gals, will help out alot