Curling Up

So im into my 2nd week flowering 3 gorgeous ladies, and one of them has fan leaves curling up, the color is still a nice green and the new leaves are just fine but all along the same node those leaves are curling up, ill have pics sometime later, ive given each of them a half dose of big bloom this last watering and the others are looking beautiful, just one plant which gets equal treatment is acting up, i was thinking heat stress but its really not that close to the light, its about a foot from a 400w hps

Is your bulb air-cooled?
Why only half dose?
I give my plants plenty of Big Bloom.
It may be heat related if it's just the top leaves.
Are they curling inwards and upwards?

12 inches is too close ,....raise up to 24 inches at least......then check the temp at canopy level ........

but the others are the same high and are loving it, i put my hands above the plant top and its not to hot, ive read another thread with someone else who had 1 plant which had a bad problem with leaves curling UPWARDS i gave them half dose cause i wasnt sure about how much to give them since i had never used bigbloom before. and the other plants just loved it, looking relaly nice, pistels on almost every node on the entire plant, nice colored leaves, not droppy, just perfect really. but this one plant has like 4 leaves that are like this, but theyre curled hella bad. i need to get pics but i dont wanna disturb them so im gonna have to wait to tommorrow.