Hello - I have the same issue on my 2018 Accord Ex....I've taken my car to the dealership six or eights times (lost count), the first time they had their collision shop adjust the side fender and hood (when finished, the fender and the hood was out of alignment) and they had the car for 8 days. Got it back, same issue. Three weeks ago I got a call that they have a fix for this issue (two way tape inside the mirror) took it in applied the fix, no whistle noise but still wind noise. Again, they called me to let me know a Honda engineer would like to look it out (great, maybe we're on to something). I took it in, after a day of diagnostics, it was concluded by the engineer the noise is caused by the "the wind characteristics" and it's normal. So, they basically told me to get used it (not in so many words)