Not sure what the fix is other than sending it to Fuji if it bothers you that much. I am going to m make an assumption that this has zero effect on picture taking, so if it were me I'd leave it alone.
Now, with that having been said how often do you clean it? My XT1 is nine years old and I can count on one hand the number of times I've cleaned the EVF. And, to clean it I use a soft brush, to brush any dust away, and if it's smudged, I use a Q-Tip with 1/2 drop of glass cleaning fluid. So in other words, I don't clean it too often.