[nsxwolf]

I really don't know! I just get this deeply uncomfortable feeling when I see that I'm going to have to have some kind of unplanned interaction with them. I'm not a terribly shy person, there's just something about the neighbor encounter.

[pcrh]

It's because you don't know them well enough. Or maybe because you haven't been "formally introduced". This makes you nervous of the impact that an accidental disclosure of information might have.

Invite them around for a BBQ (if you're American).

Even better, if you notice one of them having a minor problem, offer to help with it.

[gtremper]

I feel the same way about neighbors in my apartment building and deploy similar strategies. I think its a mild form of social anxiety.

[sliverstorm]

If you get to know them better, will you feel less anxious?

[nsxwolf]

Possibly, but I think maybe it's that I like social interactions to be on my terms or anticipated ahead of time.