Looks completely normal. The plant is using available nutrients to create roots.
Keep the rootzone clean and you will not have any problems. Foliar feed kelp meal or use IBA-K and/or NAA solutions either as foliar or directly in the reservoar. Remember that IBA and NAA will inhibit flowering with temperatures over 10 degrees Celcius.
Other way around if you for example soak seeds in NAA solutions and plant them in early spring right after frost has gone, that will promote early flowering.
IBA-K and NAA is for vegetative growth. I use kelp up intill the 3rd weekend of flowering and almost always use BAP(benzylaminopurine) on established plants at about 50ppms before going in till flowering. BAP will most certain stress the plant initially and they will need a couple of days to recover. Never spray sickly looking plants with BAP.
I'm also very intrested in Ethephon and what the addition of ehtylene would contribute with. BAP help to develop lateral buds at a faster phase than normal, ethylene will do the same things and more.
