I don't usually keep the Tesla app running on my phone as I usually only drive on weekends. I went out to my car on Saturday opened the door and drove away. Later I realized that I hadn't started the app up first. I did some experimenting and found that as long as the phone is paired with the car and in close proximity that it will work as a key. This seems to be a fairly new behavior and I like it. Now I only need to start the app up if I want to preheat the car or do some other remote function. Has anybody else noticed this?