what year are your Xs? I see a handful of '07s. Could be 1st run issues they've corrected. They say it's common but it could be 07s that come back. Just a guess. I would call out poor quality if I see it but I haven't had any craftsmanship problems in my vehicle.

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'08 X5 3.0si - Alpine White / Saddle Brown interior
Specs: Sport Pkg, Premium Pkg, Tech Pkg, Comfort Access, Aero Kit, Style 433 staggered 20s on Conti DWS
Mods: Carbon 35 tint, LED angel eyes, GP Thunder 7500k fogs, H&R 20mm/25mm spacers, clear reflectors, gunsmoke-tinted taillights
Coded: Digital speedo, windows/sunroof/tailgate close via keyfob

X5 pics at Flickr