Read up on the reticular activator. It's highly related to priming, but serves a slightly different purpose.
Basically, once something has been brought to your attention, you start noticing other things related to it with much higher frequency.
You may not really pay much attention to the cars on the road, but the moment you start thinking about what kind of car you'd like to buy next you start noticing them a lot more. Once you own a car, you will tend to pick out and notice that same model almost instantly when you see others on the road. When I started working for a plumbing company, I started noticing other plumbing company trucks on the road, and I defaulted to looking for their master plumbing license number on the truck, since I know that is required to be displayed on the truck - but the reality is, I DON'T CARE about plumbers driving around, not one bit. It's the reticular activator that's causing me to notice things I could otherwise care less about.
Once you are aware of the various symptoms of autism, your reticular activator starts looking for them with greater frequency. We know autism is a spectrum disorder, but there's no reason to discount the possibility that it is also a continuum that reaches all the way into the "full-blooded NT" side of things, especially if it really is just a difference. That would make it no different from "water temperatures" which range from hot to lukewarm to cold to freezing.
(I do like that reticular activator article, because of the part of the first sentence in parenthesis, seeing as how it is directly related to most of the sensory issues with autism.)