Very Strange Front End Sounds

[Harveyd396]

I have a 2016 M3 M/T with 47,000 miles. Overall it's been great, very little problems over the last 2 years. All of a sudden, last week, between 50 mph and up, I started to hear a strange sound coming from the front or bottom of my car. It's not very loud, not possible to record, I can only describe it. It's almost the same sound as the buffeting you hear when you open a back window, but not quite as loud. It is not related to the drive train or engine, can hear it coasting at speed in neutral. I thought maybe it could be something caught under the front belly pan. I put my car on a lift, checked everywhere, nothing seems wrong or out of place. I drove like this for a week, around 500 miles. It is always there, never changes, very annoying. I'm nervous because I'm so close to the end of my warranty, I own the car and plan to keep it many years.
Here's the real strange part, I was just about to go to my dealer and let them try to diagnose the problem, I'm always afraid to give them a problem that they have to drive my car. I was cruising on the highway, around 60 mph, and I push the suspension button from comfort to sport and the noise suddenly stopped. I push again to sport plus, no noise! Then back to comfort, the noise is gone! I have been driving now for 4 days, trying all different settings, noise is gone, hopefully for good. But this still bothers me what is happening here. Will it come back after the warranty is finished and cost big money to fix??? Anyone have ideas what this could be???