I don't know if it's a bug but when replying to a tweet, the _in_reply_to_statusid value must be _tweet.idstr and not tweet.id.
var s = '@'+tweet.user.screen_name+ ' the answer...';
client.post('statuses/update', {in_reply_to_status_id: tweet.id_str, status: s}, function(error, tweet, response){...});
If you do not do this, the new tweet will not be a reply, the tweet.id is not taken into account.
And do not forget to include the '@'+tweet.user.screen_name in the status as explained in Twitter documentation.
I don't know if it's a bug but when replying to a tweet, the _in_reply_to_statusid value must be _tweet.idstr and not tweet.id.
var s = '@'+tweet.user.screen_name+ ' the answer...'; client.post('statuses/update', {in_reply_to_status_id: tweet.id_str, status: s}, function(error, tweet, response){...});
If you do not do this, the new tweet will not be a reply, the tweet.id is not taken into account. And do not forget to include the '@'+tweet.user.screen_name in the status as explained in Twitter documentation.