I read a story once about a guy who put his laptop in an overhead bin several rows ahead of his seat, and when he went to retrieve it, it was gone. He did run down the airport corridor after deplaning and spotted a woman with his laptop bag. She gave it back to him and kept walking--she made it obvious that she just didn't mistake his bag for hers, as she didn't head back toward the plane.
What the heck? Didn't the guy confront her?