Well if it is NIB, then it should come covered in tons of thick grease that HK uses to package the pistols. That's one clear indication it's new.
Now I haven't seen your pistol first hand, but in my experience wear on the leading edge of the magazine follower is usually associated with loading and firing the pistol. Do with that information what you will. I also suppose the magazines could be used while the pistol is brand new.
Myself, I would happily take the free range time that was given to you and go shoot the pistol. I really wouldn't worry about any of the minor stuff like magazine wear or a chipped case it it was a gun I planned on keeping and shooting for a long time. :)