(Portland, OR)  --  Dozens of California-bound air travelers are delayed after a rat snuck onto an Alaska Airlines flight.  The airline reports Flight 915 from Portland to Oakland was about to take off yesterday morning when a passenger saw a rat scamper from a jetway into the cabin.  Crewmembers deplaned all passengers and rescheduled their flights.  Alaska Airlines says the plane is being inspected by an exterminator.