Naomi,

>>How did you discover that you are in someone's Twit filter? Is that a feature available to the rest of us?
>
>Easy. If you try to send a Private message to a person, who put you in your twit filter, you would get a rejection.
>

I didn't realize that, as I rarely use it, but it seems proper. If someone doesn't want to read your public messages, I doubt they want your private ones either.

>Now I was trying to figure out, what action of mine prompted it. In any case, I'm really sorry for that, but unfortunately this person would not see this message.
>
>I'm thinking of writing an apology e-mail, though at this moment I don't really know for that.

You are worrying yourself needlessly. You can't please everyone all the time. Let it go.

And I agree with you on Peter's suggestion to make the Twit filter public - no way. It's a private thing, and no one's else's business. Whatever the reasons.