the flicker is in a pattern of once every two seconds.and they do not do it all the time.
headlights and dash dial lights have a very slight flicker on 2004 Honda Civic
have the alternator voltage checked while this is happening
Normal on a lot of them because they have what they call an ELD (electronic load detector) in the fuse box. As stated to be safe , have the alternator tested. Alternator output and function/command can also be monitored using the right scan tool, that way you'll also know if the controls (PCM regulated) are working.