Drupal forum post not showing on forum index
The red box means the post has been unpublished.  You are still able to see the post, but everyone who is not a webmaster gets a 403.

Drupal.org uses a number of automated tools to detect and unpublish unwanted posts (e.g. suspected spam).  The most likely explanation is that your post tripped up one of these automated tools.

If you believe your post was unpublished in error, request it to be republished in the Drupal.org webmasters issue queue.