How was this additional information added to the question. My first thought was that it belongs to a bounty, but there was no bounty provided on this question.
Using the search hasnotice:1 is:q gzip indicates that the question is somewhat special. As far as i know is that hasnotice:1 finds questions that are locked or offer a bounty. But i don´t know why this question is so special (Its a good question with good answers, but it seems not to be locked).