Just to update this thread with results - my shop reported 2 codes... something with EMF sensor and undervoltage. Ultimately they replaced the parking brake actuator (related according to another thread). Since it was so random, I'm not sure if this rids me of the problem, but it was a high cost done under warranty before it runs out, so better than not doing anything or waiting for it to come up again.

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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