1 week old seedlings curling leaves, is this normal?

howdy, I'm a noob and I put some germinated bag seed into rockwool cubes. they are about a week old, and they look pretty good, however, I have noticed the ends of the leaf curling down. Here is my grow info:

*using HO fluorescent (t5, 4 bulbs 53w each bulb with blue spectrum 24/0 placed about 8-12" away (I started with them a little closer, but moved them a few days ago to 12")

*watering rockwool cubes with 5.5 pH distilled water only when the cubes feel dry, trying to be very careful not to oversaturate

*I have a small oscillating fan blowing on them 24 hours a day on LOW setting

*keeping humidity around 35-45% and temp around 72 degrees

I just put a heating mat underneath the tray they are in

Any help or suggestions are appreciated! Thanks!

seedlings like it a more humid. humidifier or humidity dome. I dont see too much to be concerned about

hard to tell from the photos but they look fine to me
they will perk up a bit a heating pad is used more to root cuttings and shouldnt make a difference to seedlings