Still posting everything in the wrong sections... One day...
I very rarely touch my brakes at all, so it's new to me, but could have been there ever since I bought it. Only noticed it at all after Spoons pointed it out to me
This could be part of the problem, and until recently I sometimes sit at the lights with my foot on the brake (never knew any better).
Not sure when the discs were last changed, but according to Halfrauds they're at 29.1 and 29.2mm (out of 30mm new, and 28mm being the min).
Pads were changed 1 year / 9000 miles ago.
I'm assuming / hoping that it's just pad transfer build up or something causing an uneven surface rather than warping.