Only if it's the only thing they talk about. I remember a few months back when we had a lot of celebratory threads for 1K, 5K and 10K, they just sprung out of the woodwork. But as long as they have some discussion, it's fine.
If I understand correctly, before I arrived, it was a tradition to do a review for each milestone. I missed my 10K, did a review for of one of my favourite films for 20K, was planning a tag-team review for my 30K but that got canned due to problems and my 40K blew by without nothing happening. And my 50K, as it's inevitable unless I get banned, I might do something. Probably a small review again.