Funny, I experienced the same thing somewhere around 45/46. I used to joke that I finally went through puberty because I was a AA cup (that's basically nothing to a solid A. I still can't wait to get my bra off and still walk around without one most of the time. As you'd expect, nobody notices, LOL.

I had no idea either, about the mid-life boob thing, but it must actually be a thing.