I agree, manners are becoming a lost art. We made sure our son (now 25) learned his manners when he was little.
However, as he got to the end of grade school and into middle school, we always got a laugh, since he would be almost rude to us, but other people would tell us what how well-mannered and polite he was. Obviously, the rebellion had set in. Now he is polite again and is surprised by how rude people can be. :)