While we talk about the boom as encompassing 1946 to 1964, demographers note that it really began mid-1946 and ended mid-1964. Harris, born in Oct 1964, can therefore fairly be described as Gen X.
Well, "the boom" isn't the same as the generational identifier! So saying "1964 equals Baby Boom" is right in the vernacular. She just wasn't born in the actual boom after which the generation is named.
I was just trying to help you save face / share a factoid.