Despite a warning from the head of Connecticut's Department of Motor Vehicles about lengthy waits today after the closure for Labor Day, lines at the Danbury branch aren't as long as they have been in recent weeks.  Commissioner Andres Ayala says progress is being made to tackle a customer backlog after a major computer upgrade was completed several weeks ago.  But he says people are still visiting the Danbury branch and others despite more registration-related services that are available online.  Most services at DMV branches were shut in August for a week as the agency upgraded its system.