Sorry, I wasn't very clear–it is in the Dragon, but it's not in the pressurised 'nose' part (which I believe is the part that's jettisoned in an emergency, but I'm not actually sure about that? perhaps I'm wrong). Instead, it was in the unpressurised 'trunk'.
See this image: http://www.nasaspaceflight.com/wp-content/uploads/2014/04/Z8...
"Dragon also will use its unpressurized trunk to deliver the first International Docking Adapter to enable future commercial crew vehicles to dock to the station."
https://www.nasa.gov/sites/default/files/atoms/files/spacex_...
They've previously used the trunk for a payload on CRS-2, CRS-3 and CRS-5. You can see a video of how it works in CRS-5 here:
https://www.youtube.com/watch?v=yXfOOIYWGF8
(Really cool video by the way!)
