Be careful where you out your keys and how you handle them as you walk away from the vehicle. If you hold down button 1 for a few seconds its opens all the windows.

This has not happened to me, but it has unlocked on a me a few times as I stuffed my keys into a jeans pocket.

I don't know how likely it is, but maybe something near her work is broadcasting the right frequency to make your X open up...

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BMWCCA Chapter President, Hawaii Chapter (fmr)
03' X5 4.4i, 02' MCoupe, 99' MCoupe (sold), 88' M3, 01' E39 M5