There are two badges for having your question favorited. You get a silver "Favorite Question" badge if 25 people favorite your question and a gold "Stellar Question" badge if 100 people favorite your question. Both badges can be awarded multiple times.
Hmm, I'm showing that you already have the badge, earned March 4, 2015. Mortarboard, along with its successors, Epic and Legendary, are single-award badges.
To see your progress towards Epic and Legendary, you can track them in your user profile!
Also, nice answer about events :)
This is by design.
The rules for the Yearling badge are quite simple, it divides your reputation by the number of years you have been a member and if the answer is > 200 you get a Yearling badge per year.
So if in your first year you earn less than 200, but in the second you earn more (as you have done), you'll get two badges in quick succession.
As there ...