I am having similar issues but mine go a step further. The car alarm will go off much like yours but recently it has been setting itself to transport mode. This is the mode used by the factory so they can load them on the boat or into trucks. When this happens no interior lighting works, the key fob doesn't open the doors. The interior button doesn't open the doors and you cannot set the alarm at all. The dealer was baffled and reset the system.
A week later the car seemed to go into kill mode where the car would not start at all. It has been it the shop for a week now and they are still scratching their heads. My alarm problem has been going on for over a year now.