Apple lightning cable discoloration

I bought a new apple lightning cable about 3 months ago at best buy to replace the broken one that came with my iphone 5s. The end with the lightning connector has become discolored and developed a "ring" under the rubber . Yellow/brown on one side, blue on the other. The blue part has become very soft, almost sticky. Has anyone else seen this? This cord has not faced any major trauma since I purchased it.

I always use the Apple "charge cube" when I plug it into the wall or I use it plugged into a computer USB port. I am attaching photos for you to see.