>>Easy. If you try to send a Private message to a person, who put you in your twit filter, you would get a rejection.
>>
>>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.
>
>I think this might happen by accident (adding to the twit filter), with a single click on the wrong button.
>
>This may not be the case, but it is a possibility to consider.

No, I don't think it was an accident. Have you recently noted bad message of mine?