UPDATE 7/19/14 10AM: My wife was stopped by Border Patrol at a checkpoint (photos at the bottom) while driving north in Texas, en route home from where I was staying in McAllen. Patrol inspected her vehicle and asked her if she was an American citizen. She said "yes" and they let her be on her way. My son was with her. They surprised me by coming to McAllen, and well now, we're all home safe.
Here are some photos of the border area she was passing through en route home.