I agree with Raoul on this one. When they open the payload bay on the Shuttle, it has not been unusual in the past for various tiny odds and ends to come floating out. With something the size of the Space Station, it would not be at all surprising to have a few things bobbing around. I would suspect it was something that arrived with the most recent Soyuz flight, since it's been a long time since a Shuttle has been there, and there is sufficient drag at that altitude that an object probably would not stay with the Station long. Especially after some orbital adjustment maneuver.

The main concern is probably something coming loose that shouldn't have, and I would imaging everyone would feel better if they knew exactly what it was.

Hopefully, the media isn't going to try to connect this somehow to Columbia, which is physically impossible.