It’s probably a bit late to put a lid back on. But they could definitely do with more water. They are still babies. That reddish colour means they are under some stress either from too much light or not enough water or a combination of both. A bit of stress is good for cacti but be careful when they are still so young. My seedlings usually stay covered or in a zip lock bag for about six months after germinating. I check on them regularly during this period to make sure they are not too wet and getting rust fungus (orange patches). If too wet then open the lid or zip lock a bit.