As noticed by @0naj, my kernel exploit was fixed in 4.3.1.
I try not to be paranoid, but it is really hard to explain this as anything but a leak.
The funny thing is that my “new” kernel exploit is actually the kernel exploit used by JailbreakMe 2.0. It was never properly fixed.
It stayed there from 4.0.2 through 4.3, but was magically found in time for 4.3.1. well, go go @MuscleNerd and @i0n1c I guess