Do you have the flush mount side windows? I was getting wind noise on my 2015 Vegas 24.1 at about 50 mph, and it too would come and go. My dealer sealed around the top and front of the driver's flush mounted side window and I haven't had the wind noise since.
Ed & Bev Felker
Retired USAF Col and retired Nurse
Traveling with Lily & Bella ('Teddy Bear' breed)
2015 Vegas 24.1 (E-350)