^ You guys got it. Quick detailers will cause swirls, and the rear bumper is especially bad because the particles are highly abrasive (brake dust and such). As much as that "dust layer" bugs me, I always wait and do a full wash.
2014 550i M Sport | Glacier Silver/Black/Anthracite | Executive | Lighting | Luxury Seating | Black Grilles | 20" OEM Style 303 w/Bridgestone S-04
Past BMWs: 2013 E92 M3, 2012 F10 535i, 2011 E90 335i, 2009 E90 M3, 2008 E70 X5, 2006 E90 330i, 2004 E46 330i