Another strange bug with D4, possibly D800!?!?

Hi there,

today I found the following with my D4: Most times I´m using AF-C and so configured the AF-ON button to AF hold using custom function a8.

So I can focus the camera with the shutter pressed to the first step (continous), and if I like to hold focus to recompose I hold the AF-ON button to save the prefocused distance. So far so good, focus is held, but exposure should be independent to this (have AE-L to switch with the middle of the sub dial, f6).

I see that exposure changes while recomposing, but it´s not the right exposure since when I let the AF-ON button off the exposure changes significantly (may change about 5 stops under certain circumstances)! That´s is not the wanted behaviour and it´s also not found in the manual.

Anyone else found this? Maybe also on D800?

Roland.