Chauming, your description is so vague and schetchy, I don't know what you expect people to say. Just what are you fishing for? Are you looking to out the darkest secrets of FlyerTalkers?
I am starting to agree with Rudi that your lack of detail rather suggests you did
something to get yourself in that sitaution. Also, I don't quite see how you expect an explanation now, if the airline didn't give you one at the time.
The crew must have offered some sort of explanation if only to calm the nerves of your fellow passengers. If my seatmate were mysteriously asked to leave for no obvious reason, I think I would be a little worried.
J.