When you say sounds like a window slightly 'cracked' open, are you talking like an inch or two, or ex: 1/10 inch. I'd think a seal issue would be like the latter and sound like a 'hiss' or 'whistle'. If it's more a low-frequency 'buffeting' sound could be aero. maybe the factory does a better job acoustically isolating the glass. Kind of a goofy idea, but maybe you could fabricate a test deflector (strip of thick cardboard with folded legs/supports at each end, tape) just to see if it makes any noticeable difference.