[Leica] Wear on lens iris?

[Edward mortimer <muttleykid@orange.net>]

I've just been looking at a Leica today I'm considering purchasing. Its 
in very nice condition, not quite mint but almost (thats probably a 
good thing as I intend to use it alot, I dont know how easy that would 
be if it were completly 'as new'). 
The lens seems to have a little more wear than the body, some of the 
white enamel has come out of the lines and numbers on the depth of 
field scale, but Im not too worried about that. Also there seems to be 
some wear within the lens on the aperture iris. The black paint (on the 
iris blades)has been lightly worn in places to reveal the shine of 
metal underneath. As this is the first M Leica i've had chance to use 
I'm not sure if this is normal or excessive wear for a typical lens. 
Can any of you advise? 

Regards Edd