I think I suffer from something very similar to this - similar, not exactly the same. Looking at the Wikipedia article, it says:
"...spending an excessive amount of time thinking about one's past, and displaying an extraordinary ability to recall specific events from one's past. ... can recall much of their lives in near perfect detail, as well as public events that hold some personal significance to them. Those affected describe their memories as uncontrollable associations; when they encounter a date, they "see" a vivid depiction of that day in their heads. Recollection occurs without hesitation or conscious effort."
Well, I never thought I spent and "excessive" amount of time thinking about the past, but then maybe I don't know what is normal? I can certainly remember most of my life in detail, and some public events, and it is certainly true that when I encounter a date I can, in a lot of cases, rehearse in my mind the details of that date.
But actually, for me, it is more about data than date. A bit of data can induce a whole cascade of "uncontrollable associations". It's not unpleasant, it's instructive. And it isn't done by any conscious act, it just happens.