Caveat: I have the Nomad Mk 2, but I don't believe that the eccentric is all that different on the Mk 3.
The eccentric does not require servicing, any more than a stem would ever need servicing. That is, the eccentric is just a machined chunk of alumnium. That said, you can destroy the eccentric if you ever turn it so that the screws pierce the thin end of the eccentric. What happens is that the screws destroy the threads for the square taper bottom bracket. This can make it impossible to remove the bottom bracket or install a new bottom bracket.
I learned this the hard way when I tightened the eccentric at the thin end during a tour of the Andes, and my square taper BB cup actually worked its way free and pushed my crank arm off! Not fun. Thank you, Thorn, for selling replacement eccentrics, and I am now much more careful.
Though the eccentric does not require servicing, I still remove it once per year in order to inspect the inside of the frame and ensure there is no rust there.