Instead of cutting the top I decided to try bending it and it seems to be working quite well. There are several branches coming up from below. I cut off the thick leaves that blocked the light. I made the switch to 12 hours of light, reducing the hours of light by two hours per day
Normal...not quite but definitely not a problem my friend. It's just a pigment mutation.
If you look at my lilac diesel diary you'll see she has quite the case of it as well.
Some plants grow out of it. Some don't. It's definitely not your light.
Hope this helps.