The top leaves on my GG#4 started to get brown on the edges. Initially I thought it was light burn, but the stains kept progressing after I readjusted the light distance. Is it a nut burn?
I don't think they're burned. Leaves burned by light behave differently. They twist and look dry. Your leaves look good, try to raise the PH a little to 6.5 if you are watering with a smaller value, or check the EC and play with the dosage of nutrients.