So after hours of dark, the growth that happened during dark is going to tend to be lighter, it hasn't had the light energy yet. If those areas darken up over time and the lighter nrw growth seems to happen consistently, it could be perfectly normal.
That doesn't mean your light isn't too close/too powerful. I had to deal with that, and it isn't easy to catch super early. You don't want to discover it after tips, tops, new growth actually gets burned. Early on it has a certain look. It's like it's easy to see a sunburn. It's not as easy to tell if someone is in the early stages of getting a sunburn.