Experienced growers reply

I'm new to the growing game but I'm out to a good start. I'm growing some hydro from a seed that I got out of a bag that I smoked about 4 months ago. My plant is 3 weeks old and just over a foot and a half tall with a subtle hint of skunk emitting from it. My question is: on the leaves, the outer edges (where it's jagged) are curling up, but not in the sense that they're drying out. It looks as if they're curling towards the light, but I'm not sure. Is this abnormal or should I not worry about it? Any suggestions would be greatly appreciated. Thanks.