I haven't heard of it being that, but I've heard from Aspies who have "selective" mutism, i.e. they go quiet when with certain people and/or under certain circumstances - I tend to do that myself, I can be quite a chatterbox or I might go mute. Of course NTs aren't completely constant about how much they talk either, but they don't seem to go from one extreme to the other like I do.
I suppose being generally quiet could be also linked to ASD. The circumstances causing you to be quiet might be more constantly present than they are in mine. I'm not quite sure what circumstances trigger me to flip modes - I suppose one could be that I assess social situations for safety and behave accordingly. Another might be that I find it hard not to talk about things that interest me. And I have trouble interrupting people who are talking and in asking for attention, so if the people I'm with are talking together or otherwise not looking open to my input, I'm usually quiet. Also I often can't think of anything to say to people, I'm not much good at spontaneous small-talk.
So if you see most social situations as unsafe, have little interest in most of the things you think they're interested in, aren't one for small talk, and tend to be among people who would need interrupting in order to get a word in, and your brain wiring is similar to mine with regard to talking, then you might well find that you're fairly quiet.
Maybe useful questions would be, if you've ever not been quiet, what was going on then? Did you go on at great length? What was the social situation in terms of the things I've described?