Depends. Obviously no one here will be able to say "yes. pick up your new phone today at 1PM" so it makes it moot what anyone here thinks. I have seen Apple be OVERLY generous at times, and because you bought a phone that they are desperately trying to push because of what it is, they might do it just to make you happy.
If it were me I would try, but I also wouldn't be upset if they said no or only offered to do it for the replacement fee or AC+ charge (assuming you have AC+).
As far as getting a "new" phone: if you get past the first stage that answer is still "probably". They haen't had the rush of returns to be able to refurb the C's yet like they have the S's (which by the way, are almost ALL refurb now, especially in SG), so your odds are good that it is truly a new white box phone and not a refurb YET. That might change soon.
Take it in, try, but don't expect the moon for something that is nearly impossible to see in 2 pictures that are TRYING to show the issue. If it's that slight, you might just have to live with it, especially now that it's been 30 days.