I have the correct revision, but simple mathematics seems to have escaped me... 6-17 has the sub circuit in question.
An-232 talks about this issue in a bit more detail, with it being a result of non linear input capacitance that applies to all JFET input opamps.
The OP275 manual does seem to hint at the need for specific sensitivity regarding this issue and I would love to hear more about it... phase margin 0 closed loop, symmetric rise and fall, what more could one ask for in an audio opamp?
cheers
Mark