As I think I've mentioned before, in our saga, my magus actually did teach his apprentice the Parma prior to completing her Gauntlet.
There's a widespread enemy loose in our saga, and rather than take the chance that the apprentice might be victimzed while she's out of my magus' sight, she learned the Parma.
I think there were a couple of other folks out there who said the same thing...and really, I can see a number of Tytalus magi either doing the same or effectively "stealing" the ritual from their masters. I'd imagine that Tytali expect it from their apprentices.
I'll see if I can't hunt down the thread.
EDIT: Here it is.
-Ben.