Nice, congrats on the swap.
I wouldnt worry about getting a refurb. Refurbs are tested more than brand new, and also get new externals and batteries.
I understand that if you bought a brand new phone recently, you'd want another brand new phone. And I'm sure you'll get a new one.
I had my 4S for 10 months, and in September I took it in to be looked at for a hardware issue. They swapped it out no problem, and when I checked the serial I found out it was just made September 2012. So after 10 months I still got a brand new 4S and not a refurb.
Hopefully it's perfect out of box!