Did he steal them from your FC chest?

New recruits should have restricted access to your FC chest, such as deposit only. That's how my FC operates. After a specified amount of time they are given the rank of full member and then have access to everything except gil. I would suggest having your FC leader amend your member settings if they have not done so already so that you don't run into this problem again.

Aside from reporting them and waiting, I think you're out of luck.