or you arent wetting the bottom of the medium, so the plants are seeking upwards following the water. (if they are new clones and you are still misting them, the top of the rockwool is probably getting dripped on and the roots are following the drips.)
Dip the rockwool or whatever medium (even pot full of soil) bottom first in your phed water. Ph of 6 is best for roots. Then squeeze out some of the water so its moist. Not wet, not dry.
This isnt always necessary...but i have had to do it a few times. LEave the roots on top as they are, the light will kill them off...I had one start to go green...it never grew anything though lol.