Corrosion in the washers in my Sebenza???

I think this is probably just tarnish as I have noticed it in the Sebenza's I have had and other knives that use this type washer. I have in the past used a metal polish such as Flitz and polished the washers. I don't do this too often as I imagine that a tiny amount of material may be removed each time this is done and could affect the precision of the blades lockup over a long period of time. Unless it is really bad I would just wipe it off and relube.
The washers on my Sebenza have that discoloration also. Since it doesn't affect function and is not visible from the outside, I wouldn't worry too much about it. Just clean them with hot water and relube the pivot area. That should be all the maintenance necessary.
What do you use to lube it? I have been doing a drop of rem oil or maybe some wd40 when I am too lazy to dissassemble.
WD-40 is not a lube. It does a good job of cleaning out the old lube. Rem oil is good. I invested in some of the CRK fluorinated grease. It comes in a syringe which allows pinpoint applications. This is some good stuff but usually means taking the knife apart to apply it. Of course with CRK THIS IS NOT A PROBLEM, as it would be with some other companies!
I've been using my Sebenza almost 5 years and the washers have held up fine! Just a little tarnish.:)