Apple_in_my_Eye wrote:
I think when people do that it's to sort of 'ping' you, to see if you're safe or scary. Sort of like gently poking a sleeping dog with a stick, to see if it growls or wags its tail. And sometimes they're checking because they want to pet the dog and get to know it better, so to speak.
That, I think, sounds like the most accurate and fair assessment of the reason someone would say that.
I feel a bit strange about it, but I recently found myself on the other side of this for a change, when I met a girl I rather like who seems to say even less than I do. What Apple_in_my_Eye wrote is almost exactly the sort of thing that was going through my own mind.
And I think there might also be mixed in somewhere a bit of thinking like: "you don't say a lot to me, and I'm hoping you will tell me if you're not talking to me because I'm doing something wrong. Maybe I seem unapproachable to you, so I'll come to you first and tell you what's on my mind, and I hope you'll give me the same courtesy, or at least let me know if there's something wrong with me."
If I'm right about that, perhaps the best answer would be something like "You seem a very nice person to me, but I'm afraid I am not very good at talking to people, and I never know quite what to say. I may not say a lot, but I am listening, even if I don't seem to be. That's just the way I am, and I hope you understand."
I think I'll try that myself the next time someone tells me I'm quiet, and see what happens.