slight mutations are very common. PH nute overdose, tempratures, many things can cause this to happen if your not totally dialed in...i wouldnt worry about the symptom too much, but look for the cause.
im not seeing any def signs, but i do see some upturned leaves that could indicate a bit of heat stress. if they are growing well otherwise and it is heat i would ignore it as a little bit of heat damage is far outweighed by the benefits of strong light.
but still, check your all dialed in. soild not too wet, PH 6.3 or there abouts. and dont over react whatever you do, if you think you have an issue like a def at any time, respond in tiny increments.