Sounds like something else might be to blame for the droopy leaves. I think rockwool is one of those mediums that is always either too wet or too dry. I used to use 18/6 until I tried 24/0. Cuts the Veg time down considerably and allows you to check on them anytime of the day. Not sure yet which is more likely to turn the plant hermie. The stress of going from 24/0 to 12/12 or light leaks during 18/6. But I would bet its light leaks during 18/6.
Hopefully you have selected the appropriate bagseed for your grow. Poor selection may also result in hermies.