that's the only thing i can think of, it's now only on the tallest tops, and the leaves are "shiny" and kinda mottled looking, could that be transpiration scars?
A lot of different problems show similar characteristics so Id suggest giving more info on your grow.
they shouldn't have any def or excesses at this point, in soil, getting fox farms nutes and molasses, i've also spoken with another buddy who's had similar problems, said looked almost identical the twisting and leaf damage is caused from the water getting too hot within the leaves and transpiring out, which can cause damage on tops too close to lihgts