I believe I got twice the reward that I was promised for both of the missions that I have done. I'm almost positive it said beforehand that the reward was 2,500 exp and 10 faction points, but I ended up getting two items (I can't remember if I was supposed to get one or two), 5,000 exp, and 20 faction points. Or at least, that's what the "Mission Information" says now that I've completed them.

If your pet performs exceptionally, you receive an extra item and double experience, gold, and faction. However, if your pet performs poorly, you receive no items and half experience, gold, and faction.

So as long as your pet performed exceptionally (Success), then it's working as intended