Tonight I noticed that both of my joeys were riding with mama as she went around the cage to eat and explore...one was on her back, the other was nursing. I know that sugar gliders do this, but I'm wondering what age they start??? The joeys are super young - their eyes aren't fully open yet...I'm scared that they're going to fall off and get hurt...is this normal???

Yes, it's normal.
I have seen mine run in the wheel like that.

OK, thank you. That's a relief!