In my opinion based only on the three photographs provided, the first photo in the OP's original post shows an expected two-tone finish near the muzzle. The second photograph shows what looks like fresh (post-finish) pitting at the bottom area of the slide and rear tip of the tang. However the upper portion of that slide photograph shows two (and maybe three) small patches of pitting in the slide surface that existed before the slide was refinished. The third photo puts the slide pitting in better perspective.There could also be a area of fine pitting forward of the ejection port. The frame's grey color looks a lot like other known refinished 1911A1s I have seen. But better, more detailed photographs are needed to be sure.
Thanks for a better photo of the frame. I was not sure what the frame anomaly below the slide hold-open slot in your first photo was. I still don't know, but no matter. And under your lighting conditions, I liked the very subjective "look" of your slide color better than the frame. That's why I tried to answer your original question of a possible refinish with something more objective. Surface pitting under the finish is one of those things.
As Sergio said, it's difficult to evaluate a finish from photographs taken under artificial light. I felt that the color of the left-hand of the side looked more original than the frame. Just my opinion from limited photos. However, on the right-hand side of the slide, I felt it highly unlikely that Colt's quality assurance would have accepted a slide with rust pitting under their factory finish. Even if it is just a spot refinish of only the pitted area, it's still a refinish per the OP's question to the forum. If he is looking to buy it, he has a better bargaining position.
The receiver certainly could be refinished. What I see is the original left side markings, JSB, VP, and final inspector's mark still sharp and clear. In my pinion these would not have survived in this condition in an arsenal sandblasting for refinish.