A twitter troll called it a fable when I explained that I was hyperlexic as a child due to being on the autism spectrum.
In those days, I was considered to have "pervasive developmental disorder not otherwise specified" due to being high-functioning, and this was seen as distinct from both autism and Asperger syndrome.
This category, PDD-NOS, no longer exists, as it was merged formally with autism in 2013 DSM V update.
I am not self-diagnosed and I am not late-diagnosed.
I was diagnosed and treated as a child and then the name of my diagnosis changed, which is why in the past I've mistakenly said that I am not autistic.
I didn't get my Autwarts owl when the label for my condition changed to autism, though I was grouped with autistic and Asperger kids (so-termed under the old model) for therapy as a kid.