Brake Master Cylinder problems of the 2013 Nissan Armada

I was driving along in traffic at between 30-40 miles per hour following about 3+ car links behind, I went to make an emergence stop and had very diminished braking power and ended up hitting the back of another vehicle. I had this problem before (lucky not hitting someone) and took it to my Nissan deal where I was told there are no brake problems. I have since had the problem multiple times and my dealership cannot find the problem. I have expressed to Nissan USA that the problem sounds very familiar to the reports in their open recall "tem affected: service brakes, hydraulic:foundation components:master cylinder date announced: 10/21/2013 description of recall: Nissan north America, inc. (Nissan) is recalling certain model year 2013 titan and Armada vehicles manufactured February 22, 2013, through may 3, 2013. The affected vehicles have a brake master cylinder which may intermittently reduce the pressure supplied to the front brakes. Action needed to fix Nissan has notified owners, and dealers will replace the master cylinder, free of charge. The recall began on October 21, 2013. Owners may contact Nissan at 1-800-647-7261. " Nissan says my vehicle is not affected and cannot tell me how they know my vehicle is not affected. My vehicle manufacture date is December 2012.