Do you notice a smal delay in growth after you flip the cobs on? I think the intensity and change of spectrum sort of shocks them for a couple days.
I raise my panels when I first fire mine on and then ease them down. This time for transition I went without lenses for a few days also.
I only do this as a precaution. I've only had a few experiences where my CoBs impacted a plants growth and it's only been when I've been stupid and rushed a young plant underneath them too early.