If you hit the submit button and you get an error, the username should be checked again to assure the user that the username is still available (now the check-icon is in idle mode - like the username has not been checked yet).
If you hit the submit button and you get an error, the username should be checked again to assure the user that the username is still available (now the check-icon is in idle mode - like the username has not been checked yet).