It is hard to say if the White Reception would have opened by itself. But those "slits" I think might be caused actually by too much tissue. I say too much because if you look where the slits are, the dorsal petal surface seems to actually fold over onto itself at the point of the slit.
Will this or has this ever happened before? The answer is probably a "firm maybe". It may happen again or maybe it will happen just once.
I would imagine if it were a genetic based abnormality it would happen again and again.
Something due to an unusual occurrence, as in the plant grew so well that extra tissue was created, would be far less predictable or not regularly seen in this particular clone. It would be very random.
However it seems to be a delightfully HUGE flower! I think it is very pretty.