I'd get it checked out - the fact the metal has turned blue means the composition will have been altered by heat, which can lead to cracks and brittleness.

If it were on only one rotor, and on the outer section - it would suggest a dragging brake caliper.

Because the heat marks are towards the hub in an area that the pads don't contact - and it's on all fours (predominantly the front) - is it possible that you just pounded these brakes to hard too soon, and the severe heat that 24 repeated high-speed stops would generate has caused the discolouration?

Obviously because the rotors are clean raw steel and with no road grime, you can see the heat marks a lot more easily.....

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2005 3.0d Sport - Sapphire Black
Engine : Bluefin Superchip Tune,
Wheels & Sus: Style 168s (10.5s all round), H&R RDA Spacers, Bilstein B12, Eibach 40mm drop, Whiteline RSB
Exterior: Le Mans flares, 4.6is kit F&R
Interior: Dynavin N6, Blackvue DR650 dash cams

My Build Thread: http://www.xoutpost.com/bmw-sav-foru...run-sheet.html