What may be causing issue with headlights turning on by themselves even when car is off?

My wife drives a 2007 Grand Prix - Last week when I came home I noticed that even
though the car was off her headlights (and only her headlights were on. By the time I
got into the house and asked her about it she noticed her lights were on from the
window and by the time we got back outside they were off again. Then comes last
night we get home from working out lights turn off as we turn off the car we get in the
house about five minutes or so later look outside and once again the headlights were
on, this time we could not get them to turn back off unless we turned the car on and
back off but again within about 5 minutes of turning the engine off and locking the car
the lights were back on.