CN was privatized on November 17, 1995, ending a decades-long ownership by the Canadian federal government. Just under 15 years later, CN started applying a "The journey continues / L'aventure se poursuit" 15 year logo to selected locomotives. In typical CN fashion one side of the locomotive received the English version and the other received the French version.
It's not unusual for CN or CP to apply special liveries to their locomotives. CP decorated a number of their locomotives for the 2010 Olympics in Vancouver, and several CN locomotives have received stickers for Ecoconnexions.
CN applied the 15 year logo to six of the ex Union Pacific C40-8s it acquired: CN 2107, CN 2112, CN 2113, CN 2115, CN 2124 and CN 2128. I've seen 3:
|CN 2113 in Winnipeg, June 25, 2016|
|CN 2115 near Winnipeg, January 20, 2014|
|CN 2128 in Winnipeg, April 21, 2014|
|CN 7505 in Symington Yard, Winnipeg, March 25, 2015|
|CN 7258 in Symington Yard, Winnipeg, June 17, 2011|
Have you seen any other "15 year" locomotives?
You might also be interested in LogoDesignLove's article on CN's logo evolution, Trackside Treasure's post on the logo's 50 year anniversary, and Oil-Electric's post on the "bent paper clip".