I bought a 2009 Scion Xb in April of this year and have not driven it a lot or had it for a long enough time to understand all it's quirks, it has 93,000 miles on it.  3 nights ago, I heard a car alarm go off randomly for a couple beeps, it sounded like my car, but I wasn't sure, then the same thing happened an hour or so ago (it's 10:30 pm) Sacramento time, I had been attempting to replace the map light bulbs last night and forgot to turn  off the light last night, so I guess it was on all day and up til tonight....so went out and started car just to make sure battery hadn't run down...ran it for awhile and then locked it up and came back into my house. All quiet at the moment. What would cause it to go off randomly? By leaving the map light on for the last 24 hours or so, have anything to do with it? It's the only time I heard it go off, except when it went off 3 nights ago. It just beeps rapidly for about 5-8 beeps and then stops. And doesn't repeat for the remainder of the night, I think....

Thanks I appreciate your help.