If you have an issue and go to the apple store they will most likely exchange it for a brand new one after a couple days. Apple doesn't even bother fixing broken products most of the time.
@Givmeabrek is correct. There’s not enough refurbished units yet for consumer replacements, Apple just released this watch two weeks ago. For a refurbished unit to actually be sent out, Apple has to Use diagnostic testing, and/or check the battery and overall condition before they can even send out a replacement unit, which in this case, any replacement units at this time, are _probably_ brand new.