I have a month and a half old 2018 SFS Sport with Tech Package and in the last few weeks the rattling coming from the back of the car somewhere is getting more and more. I cannot figure out where it is coming from, if it is the back door, under the vehicle or what? has anyone else experienced this at all? I would like to narrow down the options, before I take it in to have it looked at, as it is getting louder and more often as each day passes. I do have the Pano sunroof, but the noise seems to becoming more from the lower half of the car, rather than up top where the motor for the roof is located at.