the thread that Lucius referred you to was started for reason that not every user would open a separate topic for their achievements. so it's not an obligation, just moderating the forum so that others don't have to be buried about how someone reached a certain number of posts, merits, rank, etc...
Regardless, I congratulate you on your progress.
OP can have one for him, it's not big deal to me although I tend to agree when all users reaching new milestone are willing to announced in the same thread for better moderation. I agree that it's not mandatory, but things like this are much better so reputation boards don't have so many achievement thread.
The thread self-moderated by BitcoinGirl.Club has been quite active
[13 pages] since its creation, so I think a lot of user have noticed and most user have been there to announce the milestone. Nevertheless, good job OP - congrats on your achievement.