I have the same issue. My 740d is lowered with AC Schnitzer springs front and rear. I checked the heights before and after lowering. In front the car has lowered even 5mm's more than in the rear. Still the car looks like it's raising in front. I think the reason is because the front is very massive. The sidelines of the car are horizontal over the length of the car. They are not pointing down in the front as by all other BMW models. From some angles it's really disturbing me...
(it's difficult to explain because my English is bad...)