Seedling problem

hey guys! So I have a sour lemon OG seedling that's experiencing an issue. All of the leaves are curling downwards. It very well looks like a moisture problem, however, I've definitely been letting the soil dry out between waterings, so I'm thoroughly confused. I watered it the other day and it seemed to perk up quite a bit, but here we are again with the same problem.

Temp: 75°
Humidity: 45%
Soil is Fox Farm Light Warrior
Water is distilled bottled water w/o nutes

Any thoughts?

Over water and possible ph