I was at the dealership yesterday checking out the 2014 models on the lot and noticed one of them had stripes just like these. I guess it must be a new option. Try checking fordparts.com to see if they have them there. I think that would be your only bet. Good luck!
2010 Mustang V6
SCT SF3/X3 Tuner, BBK Cold Air Intake, Custom H-Pipe, Flowmaster American Thunder
5% tints on back windows, 20% tints on side windows, DG Custom Auto quarter window louvers, Mustang third brake light tint, 3DCarbon 3D500 spoiler, GT500 steering wheel, Pioneer AVIC-X930BT, Metra 99-5823CH, Shelby GT500 leather seats, SHR Chrome Fuel Door