Take a look at this video: https://www.youtube.com/watch?v=9MNHDkynOXMHm I found a better wiki site. Still find all that wikia stuff confusing....seems to be multiple sites one is awful the other is decent.
It was the quest Return to Crookback bog. While it doesn't say specifically when your supposed to get the XP. It claims you get 300 XP. I could swear I got 200 and am 99% sure that it was 200.
Never had so much trouble trying to gain clarification on something in a video game in my entire life. With that information.....my conclusion is still up in the air....I have no idea whether being level 13 while doing that level 9 quest somehow just caused me to get 200XP instead of the 300? Or whether I got the 200 and was SUPPOSED to get another 300 from finishing the quest?.....
Around min 1:47 and 2:03 he completed this quest, and no XP message appeared on the screen. But, in fact, on the previous part he received 300 XP, so I think it's normal you get your XP before completing the quest, i just don't know why in your case it was 200 instead of 300...