Can someone tell why my leaves are curling up

From the looks of it, it is heat stress. What kind of light are you using and how close to the plant is it?

It's on the lower leaves though so it might be too much nitrogen.

i'm using cfl's and the light is about 2 inches away

How much have you been feeding it

every 2 days or 3 with nute 450ppm
The rest of my plants are ok but maybe 2 of them are like this

more pictures please. and info will help also

What color light are u using? Try a full spectrum CFL or a "Bright White" those "soft or warm" white CFL's are no good for vegging and they get hot too... Do you have a fan? I agree... It looks heat stressed to me. Check the PH and temp and Humidity also.