Yeah, you can just ignore those. I'm every single one of us have attacked them, accidently or otherwise and got disconnected.
I notice they usually appear if you are out on a map somewhere and go afk. When you start attacking monsters, they usually appear close to where you are. You can either move to a different area, or just sit and rest. They usually disappear after a minute or 2.
It usually doesn't take that long to get to level 40. So try again after, or as darcel said, message Gala if you are still getting that error message.