Security Alarm Question...

[Subix]

So I went out to my car this morning and notice the car door ajar.

Cigarette lid was open, I had some red thing from my visor sitting in my seat and my CD case was moved but nothing was missing. Everything seemed intact but it certainly has my attention. Ever since someone backed into the side of my car a few years ago, the security system doesn't fully engage like it once used to every time and I tend to forget (not anymore mind you) to wait and check to make sure the doors lock.

I was reading through the forums and noticed it was mentioned that if it was engaged and you tried to open the door the alarm system would beep at you? I've never had this happen when fully engaged so now I'm wondering if my system is indeed faulty or something else is amiss.

I'm going to see about increasing the sensitivity later this evening and making sure my doors lock before departing.