I have noticed when cleaning one of my sc5000’s, that the LCD jog screen (beneath the clear plastic) appears to have dust on it. This is actually on the LCD panel and not the plastic part. I am not sure how it could get in to that part of the player, and more importantly how to remove it. I did have the player sent back to Denon for a repair under warranty due to an issue with ethernet link lights on the unit not functioning. The shape of the dust mark on the screen looks like a thumb print, so wondered if the screen could have been touched during the repair work and dust has stuck to the print? Has anyone else accumulated dust in this part of their players?
I guess this is just a general repair guy thing, since I assume you didn’t send it to the states. One of my mixers, a PPD 9000 that was repaired in Reno by them years back, had greasy fingerprints all over it and smelled like pepperoni pizza. 
The grease wasn’t fader grease, by the way… pizza grease. Smelled good, if kind of icky on the hands. It also had no packing materials in the box. They literally put it just in an empty cardboard box. That was maybe like return 8 or 9 out of 10 for that unit. I still don’t think they’d fixed the problem (or the problems happened again in-transit) and it otherwise survived the journey, so it took another trip or two at their expense to finally re-solder some switches and hot glue some rear i/o connection board inside.
Thanks for the replies guys. My unit was repaired in the UK, its not totally obvious that the dust is in there until I see it in a particular light, I was just surprised to see it as I am very meticulous about keeping the kit clean and dust free. It doesn’t get travelled much either. My concern was really that it might cause issues with the screen at a later point if it was grease from a finger print as its on the LCD panel. It’s kinda ruined the unmarked look for the deck for me, and im quite picky about that! lol!