TRIGGER

Can anybody help please ?
Put Pagid grooved discs/blue pads on few months ago - did one trackday at Bedford and worked the brakes really hard and they were faultless. Then did a morning at Goodwood, once again with no problems until after lunch. Straight after lunch I go out and the brakes are fine until hard braking at the end of the Levants Straight (braking from abt 130mph). They started making an awful noise sounding like the pads were worn right down. I didnt go back out and this weekend changed the pads. But the pads had loads left on them - and apart for small hairline cracks they looked fine.

So anybody have a clue what the problem was and what I should check ? (as I cant get to a garage for a while)