FWIW, it seems as though he was returning from Berlin having been there in some capacity for The Guardian, and not just on personal or non-related matters:
"While in Berlin, Miranda had visited Laura Poitras, the US film-maker who has also been working on the Snowden files with Greenwald and the Guardian. The Guardian paid for Miranda's flights."
"While in Berlin, Miranda had visited Laura Poitras, the US film-maker who has also been working on the Snowden files with Greenwald and the Guardian. The Guardian paid for Miranda's flights."
http://www.theguardian.com/world/2013/aug/18/glenn-greenwald...