what could go wrong???lol
these rotors were turned before going to the track. The cracks were there before 2 days at VIR, and now they are slightly bigger and more numerous . No fade, no vibration. Rotors were at min. spec for disc thickness before the event...
NO problems, but do i dare go back to the track with these?

That rotor is fine. You should only worry about cracks when they extend throuhout the whole face of the rotor. The only thing that that rotor tells me is that you were really using the brake pedal. Good work. I wouldn't worry about them. Just keep an eye on them. Those are all surface cracks that don't extend through the whole rotor. Nothing to worry about.

Bill

How were the rotors resurfaced?
Machined/turned or ground?

Any of these operations can/will introduce stress risers into the rotor.
These induced stress risers are just waiting for you to use the brakes...alot...to allow cracks to form.
This is why engine builders, after grinding & polishing rods & cranks, will shot peen all the pretty surfaces; shot peening reduces/removes machining induced stress risers, making the part stronger.
Now, don't go shot peening your freshly turned rotors.
There are other ways or stress relieving, such as cryo-treating.
But if you factor in maching time, shipping costs, cryo costs, etc, and take into consideration that the used/machined rotor is inferior to a new rotor, it makes sense to just get new rotors.

My rule of thumb when it comes to brakes is both rotors and pads get replaced when either wears out or after one year.