People who are distracted can make a wrong turn and then try to double back. They can miss their offramp. Happens all the time.
Surface streets near the airport see quite a bit of police activity (mostly minor assaults, some robberies).
But unless she somehow transferred her phone to someone after talking to her husband, her phone was in the car with her and the phone ended up near Almaden and Camden, quite a bit south of the airport. Either someone hijacked her car once she got off on the proper offramp or she came down the 280, thinking she remembered the directions, wasn't using GPS, and ended up somewhere she didn't plan to be.
Almaden Expressway branches off the 280 before it gets to the 101, and then runs parallel to the 101, so she would have had to head north (again) on the Almaden Expressway to get back to the airport. I think her GPS would have told her to head north on the 101, though.
I'm pleased that it seems LE has gotten her cell records and can plot out her drive. I just wish they'd be more specific about the route.
I'm guessing her first misstep may have involved surface streets, as well. Maybe went around the wrong block? Opportunistic crime? Is it confirmed she stopped at an ATM?