I don't think I have, but what comes to mind is where they might be in their transition. If early on maybe they lack confidence to be more outgoing, sort of shy in discussing transition topics. Maybe do not want to discuss them as they are a private thing with them. If later in transition, perhaps would prefer not to hang out in a transgender group, instead preferring to develop cis-gender friends for dating or whatever. Like hiding out among cis-genders so that others would assume that they are too.
I'm just guessing here.