Well, I admit I am an idiot and let my super draggy go into a horde of ice elementals, snow elementals, frost trolls, giant ice serpents, and a white wyrm. He died a slow death, but man, I felt stupid. (Cast recall faster, dammit! Faster!) Most of my pets rarely die anyway, yet my super dragon died.
*bangs head on wall*
Being considerably bummed out, I decided to continue training and overcome my losses. Besides, I was probably rusty for not playing UO seriously in months. And this was a chance to see if magery will really come back after death.
So I looked at his 125.3 magery. My dragon's magery was originally 125.4. Of course, I remembered someone telling me about a dev who said it doesn't matter what the pet casts to gain magery anymore, as long as it casts. That was from a long time ago, and I suppose it works the same way now.
After three more hours of training at the white wyrm's den (and avoiding hordes of icy creatures), I got that 0.1 mage back. No discord.