Upper fan leave canoeing upward. Moisture, heat, both?. Please help.

The upper fan leaves of my Grand Daddy Purp/Train Wreck are starting to fold or canoe upward. I am not sure why. I know this is usually due to either heat stress, lack of water, or lack of humidity. Im not sure it is any of those to be honest. Any other Ideas of what it could be? Or is it surely a moisture/heat problem? Please help as I do not want this strand to stress much. The rest of them seem to be relatively well and healthy. Not much If any fold on the other strands.

System:
18 girls (GrandWreck, Juicy Fruit, Blaze, BubbleGum, Cindy-99, Hashplant, Dyno, others)
1000w MH 18/6
4'x4'x7' tent.
Day: 74-77F constant 58%RH Night: 64-65F constant 60%RH
1gallon black grow bag in dirt. Mixture: 1gal perlite/ 2 gal sunshine mix #4/ 4gal Roots Organic
Watered every other day to every third day depending on bag weight. Nutes once a week, Cal/Mag as needed, the rest of the waters is dechlorinated tap water set to PH 6.5-6.75
PH steady at 6.8
Foliar fed once a week. Wetting agent (CocoaWet) once a week, 2-3 times a day foliar Mist with water.
Light height is set to 16"-18" above plant tops. Thermometer/Hygrometer set at plant height.
Avg. Height is about 10". All plants were clones EXCEPT the GrandWreck
Cold air intake to Carbon air scrubber out.
10 days or so veg on clones, month and a week on the GrandWreck
Nutes: GH Roots and Biothrive. Nitrozyme once a week.

Am I missing any Info yall need to know? Please Help me out.. I am clueless at this point as to what it could be. Thanks everyone.

Sorry about my phone camera... Best I could do. Hope it give you the idea. THanks again

Anyone Have any suggestions at all? I know the MH light makes the pics a little hard to see but its the best I can do. PLease let me know what you think.. Even if nothing is wrong it would be nice to know so I can puts my anxious mind to ease before I go to flower in 2 days..

Actually, that doesn't look bad. I'm no expert but seriously, they look healthy. Do you have any other concerns with them?

Just keep an eye on them, they may just grow and stretch out of it. If it continues and spreads they may be 'praying for calcium' as us old timers say. Pretty important at bud/growth sites........

No other real problems than the cupping. I am planning on running a watering with Cal/Mag today. I did notice that a few of the new growth leaves on one plant are twisting a little which I have read is a sign of calcium deficiency if I am not mistaken. But yeah other than that no real problems... any suggestions fellas? I do appreciate all the help and opinions I can get.

It looks fine to me, the plants are just reaching up for your light!

looks good to me . might be a little close to the light