I thought I'd swing back here and update since I had an opportunity to rebook an appointment but this time drive with the service manager. He acknowledge the whistling noise and my dealership has now had my car since Friday (it's now Wednesday) to try and resolve it. So far the window seal and mirror have been replaced. The mirror might not have needed replacing had they not broken it when removing it. They're telling me the noise persists so troubleshooting will continue tomorrow.
I would have never imagined a week to resolve a little wind noise.