Question about my CZ75 finish

[gunsandknives]

  I am no way OCD about keeping my EDC pristine.  Last month I decided to change my EDC to my CZ75B.  I'm using a nice Bianca that exposes most of the barrel/slide.  On the first day, I wore it no more than an hour...thirty minutes of that was driving.  Here's the weird part.  When I took it out of the holster, I noticed what looks exactly like holster wear on the barrel/slide towards the muzzle.  It looked like the black finish was worn away and bright, shiny brass was showing.  I'm talking bright, yellow brass.  It freaked me out a little and my first reaction was to lick my finger and wipe the spots.  With not much effort, the brass disappeared and it looked new.  The next time, same thing, slightly different locations.  This time I showed a couple of friends the "cure".  No one has a clue.  It happens everytime.  I have checked my jeans for rivets, belt, shirt, seat belt, holster, everything that could possibly touch it.  Nothing.  Does anyone out there have an explanation?     

[1SOW]

Whatever was showing was not from the 75b finish..  Guessing it/you  rubbed up against something that should clean off.  If the finish gets scraped/rubbed off you'll see shiny steel.
If your bbl was oiled maybe the oil  reacted/ dissolved something it contacted.  Any Hoppe's on the bbl?
Did you check the interior of holster?

[gunsandknives]

I haven't used Hoppe's on the frame, only on the barrel, lilterally.  The holster doesn't touch the gun where this is happening.  I can guarantee there is no metal on metal.  My first thought was Levi rivets but there aren't any.  Surely someone is going to read this eventually and have the answer..thanks.

[1SOW]

What "specific" ammo are you shooting?

[Tyerone]

Car seat belt?  Something in the car...

[Tyerone]

... or somthing you do habitually, like propping the screen door open with yor hip as you unlock the main door.  Maybe your particuar strut while walking scrapes your watch against it???