The red one is a new Metro, the black one is an older Metro... Hmn, got me wondering if maybe the black one has just been played enough to where the satin nitro finish wore smooth. That's starting to happen to my NYC; it's starting to look a bit glossy. I'm OK with the feel of it, but the cure is to buff _lightly_ with a Scotchbrite pad to knock the gloss down. Or maybe a previous owner polished it with something...
I gotta doubt it's from the stand, since the stand only contacts the neck in a very small area.
@JohnnyTog the advice to contact Lisa is an excellent idea. She was most helpful to me when I asked about extending the upper horn's strap button a little to make the balance more to my liking.