I did notice she had several hundred FB friends, I think, and much activity, so she used FB a lot and she used it a lot before she posted the "hitting the gym" comment, which was maybe on Monday? Or thereabouts? The "hitting the gym" struck me as very casual, something I might say to my friend (if I ever went to a gym) tomorrow, for example, on a normal day. I think that is what has so many people stunned, that she could write, or even think, anything remotely like her everyday life at this time.
I am NOT comparing the losses, but when my dear kitty passed away two years ago, I stayed away from work for two days as I knew I would cry and did not want to make a spectacle of myself. I am pretty much on the internet all the time and the only time I was that week was in trying to find the nicest place to take care of his body, etc...we all project our own personal experiences in cases like this, as there is little else we can do but compare to our own lives. And that is where we are finding the oddities.