I would say "NO". People have been interested in keeping track of important health-related things for centuries. Fertility and menstrual charting easily come to mind. What is happening now, is the same caliber just with ease of accessibility and usability, less waste of resources (no paper involved here) and a different genre of community element.
I was interested when this new group popped up. I said to myself "quantified self, what is that?" I read your greeting, and I think I understand what you are saying but please correct me if I am wrong.
It might be possible that "quantified self" is a trans-cultural trend, more than a fad. I say this because of the connectivity of the internet and presumably the widespread usage of this website and it's tracking devices. Maybe that would be a good poll... asking what continent people using this website are from.
I myself, may not be a very good technically-inclined self-quantified enthusiast, as I don't come on here regularly enough to track the few things I have as trackers. I do however, track my menstrual cycle via a real-life calender and find it of utmost importance.
Was Christianity just a fad? Was science just a fad? Was cosmology just a fad?