I have seen pictures where she's crying and I can't
I guess you are refering to these pictures:
Watch more pictures from the event in the Gallery.
The Firefly 10th anniversary panel at San Diego Comic-Con 2012, gathering Joss Whedon, Nathan Fillion, Alan Tudyk, Summer Glau, Adam Baldwin, Sean Maher, Jose Molina and Tim Minear, proved to be an hilarious, intense and emotional panel. Here's the video from a very heart-warming moment at the end of the Firefly 10th Anniversary Reunion panel where Nathan Fillion, Joss Whedon & Summer Glau break down in tears at fan support, and Summer Glau and Sean Maher hug each other. Joss then explains why the fans mean so much to him.