Some plants are clawing some aren't..... any suggestions?

Hello forum. First time poster. I have been reading and searching on these forums for about 9 months. Today I decided to finally throw an issue at you guys and am hoping you can help.

I have a vertical set up with about 30 plants. All the plants are doing great except about 4 of them. They are situated in the middle and are the ones getting the most light. They are curled down but still managing to grow and just started flowering (as I just switched light cycle). All other plants are EXTREMELY healthy.

PH is stable
Nutes aren't way high (1000-1200 ppm) plants are big enough.
I am using hydro btw and am watering every 3 hours only when lights are on. I have good outtake and very good circulation also. I am thinking about isolating those few and just hitting them with less light and only PH'd water for the next few days.

They seem healthy other than the obvious curling leaves. Since I am just starting to flower I don't want to mess around doing a bunch of cat and mouse games. I know it's very hard to pin point reasons why but figured I'd hear what everyone has to say.
Thanks in advance for any help!

Here is a pic:
http://i909.photobucket.com/albums/ac292/jolly420meds/leavescurling.jpg

What are your temps? Looks like they are perspiring faster than they can take in. I would also give the underside of the leaves a nice cleaning before you go into flower.

Temps fluctuate. Seems to stay between 70 and 80. A hot day it may peak over 80 but nothing crazy. That is some food for thought though. I just added two more fans in that area for recirculation.