Hey guys, haven't gotten it fixed yet. When I brought it in pre-crosscountry trip, they claimed they couldn't replicate the issue of course, so I had to embark on my 3400-mile trip worrying about it the whole time.
I've started shooting a video at least once a week on my phone documenting how often I hear it, so maybe that will help me get it fixed next time. I'll keep this thread updated.
2009 BMW 135i - Alpine White/Coral Red - M-Sport+Premium + 6-Speed Manual