Tip of leaves are curling a bit...is it normal though?

Hey everyone. I'll admit I've been a pretty over protective grower since this is my first time but from all the threads I've searched regarding curling tips, they come to 2 conclusions and it's either a def. or its just normal... anyway, here's the scoop.

Plant is about 4 wks old.
In some fafard 4p (fertless soil)
4 23 w cfls over top
pH is about 6.0 ( not sure of the run off pH)
there's no discoloration on the leaves.
It was doing it for about 2 days and last night
i gave it some shultz 10-15-10 at half strength
temps are at 75-85 and the humidity is right around 50%

but the tips are only curling about the last half inch of the leaves...and they're not dropping at all...
can't post pics since i'm at work but i'll throw some up there when i get home.

doesn't curling happen from the temps being to hot? not sure on that one but i think so.

Anyways my plants curled a bit and it wasn't a problem

Here's a pic. tell me if it's normal or not

any thoughts?

never seen that before where they curl down, but honestly i wouldn't care to much to spend that much thought on a plant isn't worth it. Its no major problem if the plant is as green as that and lookin that nicely really. I mean those vets on here will tell you its a huge problem that relates to your ph being off by .01 and you need to add this old formula of cheetos and gatorade to save it.
You still gunna get some weed at the end man. You shit looks good from my grow which was similar to that in the sense of it having some minor problems turned out fine. Dont worry about it and see what happens.