Oxidized castor oil? Ask SIG, I don't think I have seen this. It could be gum, but not supposed to be there if Bakers AA. Gum does not cause varnish, that is oxidation. Gum is a greenish white material from the husk of the castor bean. If present it could have poison. I suspect it is oxidized oil. Or come to think of it could be a small amount of moisture that has gotten into the bottle, condensed and mixed with oil it would be white in color. I can't really tell from your photos as the light is silhouetting the clouds.