Seedlings 1st True Leaves Curling inwards and down. CARAMELINO.

Hello All,
I'm asking for advice on my first ever grow, currently running 3 strains in a 4X4 under a the Spider Farmer SF4000 LED, Distance from canopy; 34 Inches/ 86 cm.
CYCLE: 18-6.
Temp ON: 27 Celcius,
Temp OFF: 19 Celcius
Humidity: 25-35 %

It's day 9 since germination (wet paer towel method) and day 6 since all the seedlings have been planted in soil, using CANNA TERRA PRO +.
As you can see in the images the most vigorous of the 4 plants is the GELATO.
My concern is with the CARAMELINO which is showing bad signs as the true leaves are curling inwards and also down. I've kept all of the seedlings under a plastic bag dome to maintain humidity and watering with a spray bottle twice a day Ph 6.5-7.0.
I'm running two CARAMELINO plants and the other one appears to be doing well.
I've read that this curling might be caused by over-watering . I have now removed the plastic dome from all seedlings and given them time to dry out and see what that will bring. Just asking if I've identified the problem or is there something else causing it, Thanks in advanced

Here is the picture of the healthy CARAMELINO that i'm running side by side.

Alota sticks in your soil no good for babies u wanna get rid of large debris 4 1,, next time u transplant. Your humidity is too low and your day night temp difference is too high u wanna keep 5c difference or lower

Thanks, humidifier is arriving tomorrow. Will bang a heater in the tent for lights OFF.

You need to pet them for a bit. Stroke the stem and the leaf. It helps them grow quicker. Not too hard though as you can cause some lethal damage. Good luck.