The leak may be attributed to poor stamping and subsequent bonding/welding of the roof panel onto the side pillars. Also, a defective weather strip on the roof that hides the water drain can allow water to run to the side and unto your door but this is unlikely because the door itself has a rubber ring seal around it. I hope this is not a body issue. If it is, no worries, a reputable body shop can take care of this easily and Nissan would have to pay that bill under the protection of warranty. Thankfully, you're a US customer so this should be resolved with no hassle!