The reason growth has slowed and they're showing a little droop is because they were transplanted into the 6" cubes 2-3 weeks too early. Transplanting seedlings and young plants too early will always cause young roots to become smothered (no oxogen) and overwatered. Next time, keep them in the one inch cubes for a full 17-18 days after they sprout and then watch explosive growth a few days after transplanting and moving them to an HID light. Peace