Wow, my brother (2010 X5 4.8, Nov 2009 build) has the exact same problem, and he does not park in the garages... The service dept/body shop told him the same BS story... And I saw another 07+ X5 with the exact same problem this past Sunday parked on a street in NJ...
I dont have any problems with my 08 X5, so it could be a build quality/bad batch or something like that.
Hers : 2015 328xi MSport Silver/Red
His : 2016 X3 35i MSport Silver/Mocha