How was it measured? Remember, flat calipers only measure the thickest points. Min thickness is the thinnest. A rotor micrometer (I soooo want to say "caliper") has needle points and will seek the low points for true min thickness. When you're fussing over a few mills, those needle points make a difference.
Brembos should have the min thickness cast into the webbing of the rotor. The number can be hard to spot. I just went out and looked at my Convert -- 5.7mm. Obscured by rust (yay, cast iron!). I had to roll a few degrees, search, roll, search . . .
