Interesting thread. I'm sure I posted something like this before.
I grew up mostly in the 60's. Unless you were seriously handicapped, you were considered normal. Anything short of LFA would have gone unnoticed.
I definitely had more social problems as I got older. Around age 6-7 I realized that I needed to act more like other kids to avoid teasing and bullying as much as possible. Mostly I was able to do that until 7th grade. (Don't they say middle school is the worst?) I was unable to fool my parents though and I got into more and more social related problems with them as I got older. Age 8 - 13 was the worst. Their perception was that I was doing things wrong on purpose and needed more discipline. My perception was that I just didn't understand what I was supposed to do and I simply needed more explanation. For awhile I was convinced I must be a bad kid because I couldn't figure out that stuff on my own.
I had some friends who lived close by in the neighborhood. I was the social follower, doing whatever they did. I was sort of the "interest" leader though, as I had interests I pursued whether anyone else cared about them or not. My mom has told me I was content to play by myself. Some of the interests I had were taken up by the other kids. I was often dismayed that I got punished for only doing what the rest of the kids did, never knowing (even today) how they got away with things and I didn't.
We moved after 8th grade and I spent my freshman high school year in another state. I discovered I had no idea how to make a friend and didn't have one the entire year plus we lived there.
The rest of my high school years were spent back in a city near where we used to live but I attended a different high school than I would have if we hadn't moved. I might have made no friends there either if the school didn't happen to have a club that was my main interest at time. I made a few friends there. High School is where I was farthest behind socially. There was a number of social groups on campus but any attempt to join them failed. I often felt like I was an observer looking into a terrarium watching the inhabitants inside without a clue as to what they were doing. I suppose the kids did normal social things like parties, dances and sports but I have little recollection of that. I find it quite amazing that I made it all the way through high school totally unaware of anyone having a boyfriend or a girlfriend. I was really far behind. I spent pretty much all my time, including social time, pursing one interest.
So yes, I believe aspie traits can show up past one's earliest years.