Disclaimer: I've only done one grow so I'm pretty new at this.
Maybe your plants want to be watered since the last time you watered was two days ago. You may not be overwatering, but could you be underwatering? Does water come out of the drainage holes after you pour it in?
Another potential problem I see is your lights aren't close enough to the top of the plants. It looks like you have the lights right next to the very bottom leaves in your pics. How is the plant supposed to sustain itself when the only leaves getting any light to photosynthesize with are the smallest ones at the very bottom? Try making the lights level with, or slightly above the top of your plants.
edit: I've heard some plants react negatively to 24 hours of light and no dark, so you might also try switching to 18 hours light and 6 dark.