I completed the desomg and pair valve removal on a 04 retro, a couple months ago I went in and just pluged the pair valves and finally got around to going back in and putting in the block off plates. On removal of the pair valves I noticed a heavy black almost soot like color to the inside of the pair valve and the gasket/reed assembly. I have doen this mod twice and have never noticed this before in fact I looked at an old reed valve that I had removed some time ago and there was no black color at all, look almost new, any thoughts would be appreciated.