I'd heard about this happening with the D700 at least once in the past, and I'd hoped it was a rare phenomenon with cameras more recent than the D200, but it seems not!!!
So far my lightly-used D700 isn't showing this symptom, but the rubber panels on my D200 failed badly, with no obvious 'provocation' except my appropriately-firm grip while using and carrying the camera.
So ... to make my main point here, and to join you Bob in venting some steam ... I am frankly amazed that Nikon hasn't yet adopted a far more durable 'interface' between the camera body and our hands!
Besides our use of the viewfinder, our grip on the camera is after all the most intimate contact we have with these otherwise wonderful instruments. When that grip becomes uncertain and/or uncomfortable, it has a major negative impact (speaking for myself at least) on my confidence and assurance while 'deploying' the camera from rest, up to my eye.
(I could go on .... )
C'mon Nikon ... please make this a non-issue in future cameras. These 'creeping' rubbers are distinctly UN-classy, and they're out of kilter with our cameras' high specifications in every other respect!!