I haven't seen much discussion about this type of failure. so I don't think it is a common problem. My suspicion is that whatever caused one side to fail in your case also impacted the other side.

If a problem is reported before the warranty expires, a dealer will nearly always work to cover it. However, if it wasn't reported before that date, it isn't usually covered. That suggests you are out of luck. What you may want to do is see if another dealer or shop has a cheaper way of fixing them.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue