Well, I just got our ST back and ... "could not duplicate owner's concern".
Admittedly this occasional whistle is a very minor issue, but it still bugs me. Think I'll wait a while, maybe for my next service in a few months, and see if Ford has a TSB or there's some other kind of documentation that will help them figure it out.
Amazing that my 70 year old ears, with tinnitus, can hear the whistle and the fact it goes away when the mirror folds back. Maybe the Tech has gone to one too many rock concerts and just can't hear whistles??
Other than this, the remainder of my service was fine. They changed the oil & filter, topped up the coolant (which came from the factory with the level below the "Cold" line), and fixed a loose handle on the passenger side rear door pull. I was kind of afraid that they'd need to replace the door pull itself (whole door panel and the insert with the power window switch), but it looks like a "repair" did the job. Everything else inside is tight as a drum. I had also asked them to check for loose or missing bolts and they checked the torque on both front and back bolts on the undercarriage with a report of "nothing wrong." Must of made a little difference as I sometimes heard kind of a low pitched rumble in the rear, sort of like a loose shock sounded like back in the old days, when driving slowly through our neighborhood. Same road, same speed on the way home and it seems to be gone now!!
Cheers!!
Ken