Magnolia x 'Sue' (Arrowhead)

This came to us as Sue but is clearly different from the old plant Punnett grows as Sue; our plant is shrubby (a few years back the rabbits grazed it to the snow line and we let it grow back from the lower tier of branches, but it was shrubby even before the bunnies molested it.) Our ‘Sue’ never has a hint of mildew (unlike Susan as Dirr describes it) and produces its deep pink flowers continuously from spring until frost. Its now late November and I think there are still a few flowers hanging on, it is never out of bloom and attracts considerable attention. I could believe the parentage of stellata rosea x liliflora nigra; perhaps this is a point mutation out of Susan?