My 2018 Titan rolled backwards while parked and it just started doing that. I bought this car brand new and had it for about 2.5 years. It only has 15K miles. The first time it rolled backwards I was in it. I parked and it rolled backwards about 2-3 feet. The ground was covered with a little bit of snow. The snow had just started. I have parked it in the snow before and has never done that.The second time I parked it in my driveway and I came out in the morning and the car had rolled at the end of my driveway. I brought it to the dealership and they’re telling me to use my parking brakes when I park the car, which I have never done before and I didn’t have any issue. Another thing they said is to change my tires, due to the tread depth being at 4/30. But the tires weren’t a problem before because the vehicle rolls down it doesn’t slip. The dealership also advised me to put it in 4wd when parked. I never used the parking brakes when I parked my car. My driveway is not a hill its a slope about 8 to10% degree angle. I also videotaped it 3 times while putting the car in parked, the ground had slush and you can see that the car rolls backwards about 4-5 feet. I’m asking to see if anyone has had the same problem. I appreciate any feedback.