the AP exams began in 1955 or so (hard to find dates), so that's 112 years.

Except the quote was:

that would be standard fare in a modern high school course in AP calculus.

So that's some more years, but I don't think it's really germane. I'm not saying that the time gap proves she's a genius; rather, the time gap makes it harder to ascertain.

On another not-imo-germane-to-the-discussion-note, mathematics education was more or less overhauled during the post-war period in many countries. Mathematics education as an academic discipline, I believe, was an innovation of Klein's that fell out of his work in geometry.