I had same prob - can be alarming and take a day or so for normality to
return. Rolls San Marco saddle. Corrected it by tilting forward by one
click which made huge difference.
Padded shorts can make this sort of problem worse by generally
constricting the whole undergrowth so I don't always wear them. Also
regularly swapping alternative saddles is good idea - the pressure
points are likely to be different.