I purchased my '99 S80 with 48k back in June, so far the car has been great. The one thing that I have noticed is that when I lock the doors with the remote my rear left passenger door does not always lock, although you hear the lock noise. When you start the car the next time it says the Alarm has been triggered even though it has not. Should I be concerned?

 

The door latch/lock assembly is bad.

Best to replace it.