I enabled FileVault on my Yosemite Mac, and selected the "Allow apple ID to reset password" option.
I paid attention to all the dialogs and though they said to write down my recovery key, it was never shown to me.
Did something go wrong? When I did this years ago with FileVault 1 I was shown the key.
I tested using the Apple ID "change password" function and it seemed to work OK but I'd like to have a copy of the key written down as an extra safety measure.