It usually means that if the ABS system has to take action to control a locked wheel, or shift the braking forces front to rear then it won't respond correctly.

Check that you haven't got a pond in the trunk affecting the electrics and modules.

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Me:
Current: 2011 E71 40D Vermilion Red/Beige Nappa

Wifey:
Current: 2012 R80 Countryman SDX Green/Cream