I also broke a pair of the Dark Grey ones last week changing lens. Mind you, I have changed out 100's of half jacket lens and this was the only one that has ever broke. And I had to really tweek some. This one just snapped.
My guess is there was a batch of these that have a problem.
DEFINATELY a warranty issue that O will take care of. :)
The picture color is screwy, but it is Dark Grey and near the same place yours broke.