This object has a very defined shape and this time cannot be mistaken for space debris, bad pixels nor camera malfunction.
Here are the links to the official NASA images:
http://eol.jsc.nasa.gov/sseop/images/ISD/highres/AS08/AS08-14-2534.JPG
http://eol.jsc.nasa.gov/sseop/images/ISD/highres/AS08/AS08-14-2532.JPG