Cute name for a condition known on a number of engines. It is my understanding that the (or maybe one) cause is heat percolating to the top of the casings and the assymetrically warm rotor going out of round for a time after shutdown.
I have had Garrett TFE 731 LP shafts prove hard to turn during a brief turnround. On this engine there was an instruction that on a short turnround, of some specified duration, the fan had to be turned 90 deg before start. Given that the fan is geared down about 2:1 the inference is that the cool lower section of the rotor will then be at the top and temperatures will even out. That point however was never explained and this is my guess.