Sure looks like surface corrosion. Perforation means that you would see it through the outer doorskin from the outside, when the door is closed.

I would get it fixed, and not let it go further. A body and paint expert could advise what that would take.

It never hurts to ask your dealer, but I would be asking them for some type of consideration based on it not meeting your expectations, and not trying to argue the specific warranty terms.

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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