In my professional opinion, and only going by the photos at hand, I would say the gun has been refinished.
1) The slightly "plum" color to the slide in some of the photos.
2) The rounded edges on the seam around the striker block when looking at the gun from the rear.
3) The slightly obliterated s/n on the slide, most noticeable in the last digit. ("5")
I'd say that the gun has been hit with a buffing wheel at some point in its life.
(Also, rule #1 when bidding up a collectible gun: If your spider sense tingles at all, your spider sense is probably right.
There will always be another gun.)