Looks good to me. I think it probably is the light is a little too close. It just seems to be way too uniform (indicative of something like light bleaching) to be something going on with the plant / medium chemistry. That wouldn't be so uniform across the plant like that. I haven't used an LED before but I have read countless times how their intensity can do exactly this. I don't think it's necessary this time around, (unless you want to or someone asks you) but next time you need to include a lot more details like what you're growing in, light distance, fertilizer strength and schedule, watering schedule, pH, temps, really anything you can think of that could influence your plant in any way in your first post. If ya don't, a lot of people won't even bother responding
It might possibly be wanting more ferts. Noticed some yellowing leaves down below. I know that's common in flower, but you've got at least another month to go. Get a second opinion before you go and add more fertilizer though.
Beautiful flowers, nice grow. How long did you veg for?