I tend to use spoiler tags or the like any time I make anything like a definitive revelation regarding a significant, book-spanning character, regardless of what book it's from. It's mostly just a courtesy.
Wizard-like power is relatively rare to
notice when you're not particularly looking for it. But then, the Council as a whole doesn't do much to search these people out, even in the best of times, unless they're causing trouble, and Harry isn't a whole lot better (yeah, sure, he has pamphlets in his office, and he's in the yellowpages, and he makes himself known in the community, but he doesn't do a whole lot actually to search them out until the Paranet gets set up to help do that
for the Council)
Dresden,
without expending any particular effort to find such individuals, encounters them possibly FOUR times (
really should count here, and possibly even
, since we have no clues as to how powerful she actually was) over about a decade