Not sure if maybe I'm just crazy. This cub was born in my pride.

https://www.lioden.com/lion.php?id=794231162202

I could absolutely swear this cub had a common base when born. I never got the acheivement for having a cub with a special base born in my pride. I sold this cub, got a notification it was bought out. Clicked on the link in the notification, said cub does not exist. I assumed the cub had been killed or otherwise. But when I looked at its mother's cubs bred page, there the cub is, recovering from a trade cooldown and now with a special base. I'm so confused what happened. Why didn't I get the special base bred achievement? I swear this cub was not a special base when born or I wouldn't have sold it. Just confused. Thanks!