Our PDD-NOS symptoms were largely sensory avoidances of all types (oral, tactile etc), repetitive play and language delays. A little bit of everything but none was serious. Maybe because he was a boy or maybe because his language delay was still substantial at 2.5y, the psychologist gave us an ASD dx. The symptoms have disappeared or disappearing, so it is similar to what you are describing.
IME it is worth watching as the kids make leaps in social development through elementary-- there are a few moments where all of a sudden a light bulb turns on and the kids get new awareness of themselves, each other, and their social powers. Keep an eye on whether your child develops alongside peers in this regard. PDD-NOS (ASD) looks really different in elementary than it does in preschool, especially in a gifted kid.
We had concerns about reading comprehension because we were told we would have those issues by our psychologist who noted his hyperlexia. So far, based on scores it doesn't appear to be the case, but from reading ASD boards, it seems like the real struggle for diagnosed kids comes in the later elementary grades and he just finished the 1st (7.5yo) - way too early to tell, despite very high 90s in the reading comprehension, spelling, vocabulary and math.
The thing to watch for a kid like this (again IME) is comprehension of perspectives in reading, and making inferences. As they move from understanding basic content to understanding things like the motivation of a character, or the angle from which a text is written, that is where comprehension issues can crop up in a strong reader with PDD-NOS / ASD.
