There is really not a good fix... attempts using a cold blue will make it look much worse and out of place, as it stands now it's "honest" wear and tear. A reblue will devalue the gun more than that one flaw in the eyes of many secondary buyers.
I know right now it grates on your nerves with the gun being a recent acquisition, but that will fade with time and the enjoyment of shooting it.... don't make any decisions now, go have fun with it, it can always be re-blued at a later date, if it still bugs you.
I mean... If I can come to love something like this after a while, yours is a piece of cake: