Black Line printing in Negative

I am using an Epson 3880 printer and I have been noticing a vertical black line that is printing when I have a smooth gradient. It’s possible it is doing it in textured prints as well but is not as visible if it is. As a result I get a very subtle white line in the resulting print. Any ideas what may cause this. My first thought is there is some damage to a single nozzle on my print head that results in it slightly misfiring but that is just a guess. Any other possible culprits?

This looks like either a head alignment issue or a dirty encoder strip or both.

First check the encoder strip for schmutz.