You know what.. If the mags work, then i wouldn't stress about a little wear like that. You're going to end up getting more mags anyway right? Always good to have some extras for the range and for backup.
That's funny you ask about the Mk25.. a few people have asked about it and one person bought one. I've never owned a Sig. And I really don't know how different it is to the 226... or the old 226 navy model other than the metal treatment and anchor (like the 226 navy). If you like it, by all means get it and let us know what you think.
For reference here are 2 pics of mine. not great pics, but very little wear. On yours though, it looks like there are some scratches from something other than ammo. But as long as they feed and work properly, don't worry. That's the most minor problem you could have. I wouldn't even really call it a problem... but I get wanting everything to be sparkling new!