User blog comment:Omega natsu2/Chapter 368: The Third Seal, Predictions./@comment-5172158-20140119151448/@comment-7418318-20140122163613

Yes, but if Jellal thought it was an initiation ceremonty without knowing what exactly would happen, he could still have seen fit to show up in person to be on the save side, without knowing or later noticing that the seal was cast on him.

It could have been something as simple as the guild-member stamps for regular guilds that's done to every council member, but which was also used to slip the seal onto the chosen three.

Seeing as how the Fairy Tail guild stamp is also tied to seeing Mavis and the magic buff on Tenrou, even the seemingly simple and harmless process of putting a stamp on a person can have great magical consequences.