Mine does this too - has since we bought it last year. Tried to recreate it at the dealer for a service tech and was unable to do so. Going to try again in a few weeks to see if they can fix it.

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2001 X5 3.0i (PP/WP/AP) Traded at 213K miles
RARE White on Black - Why does everyone get Tan??
First E53 with 215s on XOutpost!!