1937 Mauser, Discovered Non-matching

[mauser]

I have had a 1937 Mauser for a few years that I love. The gun is an honest 90% late year with a mint bore, and all matching except for the magazine, or so I thought.
It has mostly sat in my safe for the last 3-4 years, but recently I read on, I believe, another forum, that it is good for older guns to strip them down, and soak them in oil for a while. It sounded like a good idea, so I did, and I thought I had done it before, but this time I really looked, and all the little parts had a 60 on them, even the pin that holds the toggle to the upper receiver.
I all of a sudden notice that the small number on the hold open doesn't look like a 6-0, but a 6-something, and I get a flashlight and it is a 64!
I was understandibly upset, especially with the condition of the gun, that does not look like a weapon that has seen much use in its 70 years of existance.
Oh well, I used to brag to my friends about what a good deal I got on this luger, now it seems a little more in line.