There is even a post here in the forum.
A person saying that a clan mate got Quiz Medals for categorization.
And it was not the only person apparently...

Cruel.

Mine and Cruels clanmember got the message
"Today, 13:56 For the 350 correct quiz categorizations, you received 20 quiz medal!"

Its a fluke though as he didn't get any medals. I guess admins are working on it.