I created a new Virtual Server named mydomain.net. This server has enabled as feature MySQL in this way I got a database called mydomain.
1) Delete this database and check the privileges from terminal inside mysql prompt with this command: show grants for mydomain@localhost; Even you deleted the database its privileges are still there. I revoked them manually.
2) This is not happening when you create other databases having different names than "mydomain". Their privileges are revoked once you delete them.
3) I created again mydomain database then I deleted it. Checking its privileges their are still into the database.
As conclusion, if the database name is "mydomain" the privileges are not revoked like for the other databases. You have to revoke them manually.