I had that happen once to a tub....must have been putting it away wet caused the fats to expand a bit in the soap. What I tend to do now with soaps I load from the tub is let it air dry for 24 hrs and then cap it. As far to use or not to....its ok to use it, as long as there is no discoloration or odor its good to go.I've have a tub of Cella (red tub) for about 3 months and it has developed small white lumps on the surface. The soap is in my regular rotation and lathers and shaves like I would expect.
Is this typical of Cella (like the cracks in MWF) or is it an oddity?
All of my soaps such as Tabac and MWF are in containers with loose fitting lids which allow the soap to fully dry, unlike the Cella tubs which have a screw top lid. If you intend to use your Cella regularly then I would not worry about it too much but perhaps leave the tub open for a while for the cream to fully dry after use. When I used to use Cella I loaded it onto the damp brush straight from the tub and it started to turn yellow after about two years of regular use, but was still fine to use even after that. I suspect that products such as Cella are not intended to be used once a month as part of a huge rotation of soaps and due to their relative high water content will not last for years in the way a triple milled soap may do.I heard that getting water in cella tubs is no good and leads to degradation. You should just scoop some out onto your brush and keep the soap dry.