Cosmetic Correction (adds hot pixels)?

[ngc1535]

Hi,

In Cosmetic correction using the Master Dark method- when adjusting the sliders, when small sigma values are reached some bright pixels *appear*.
It is a very small number of  them- but still, this seems like an odd thing.
(I can make a video- but first let me know if this is an expected behavior.)

Thanks,
Adam

[ngc1535]

I would just like to add... I see the effect when using the realtime preview.
Perhaps this is simply a display thing.