I'm not sure, but I'll just tell you that this used to happen to me a lot. In the past, when I level up I seemed to get sometimes four messages at a time from my teacher saying things like "I have a new spell for you to learn," or "Come see me for a new spell," when there really wasn't anything. It was very annoying, but recently it hasn't been happening. I don't know if it was fixed. I will ask my sister about this, since she is a level 36 life wizard, and she may remember if there was a spell quest. If she says there wasn't, then maybe this is the same glitch.
If you've played the game from more than one computer, then triggering the dialogue on one doesn't save it on the other, so then when you play on the other, the game thinks the dialogue hasn't been triggered and gives it to you.