I dropped my wife off downtown in her car and she had the key in her purse. The car did make a weird beeping noise as I drove away, but I had no idea what it me

I dropped my wife off downtown in her car and she had the key in her purse. The car did make a weird beeping noise as I drove away, but I had no idea what it meant and I was pulling onto the highway which would have been a bad time for the car to stop driving on me.