On page 180 of the guide, under troubleshooting, it says that the gap is a "necessary manufacturing feature." According to the manual, friction between parts can cause the gap to widen over time. The listing seems to rule out a manufacturing error.
Still, not too many Galaxy Note 4 buyers are going to want to read about a gap that will get wider as time goes on. This looks to be just the beginning of what will no doubt turn into a media circus, especially in light of recent events with the Apple iPhone 6 Plus. Stay tuned.
source: Samsung, GalaxyClub.nl (translated) via AndroidCentral