Looking at the symptoms of pitting on the surface, I can think of two suspects
a) cold damage -> Did you leave the plants exposed to cold or cold water?
b) mite infection. -> I have not seen mite infections on paphs. anyways, check the underside of the leaves for mites. rub a small piece of cotton dipped in isopropyl alcohol. if you see orange/red spots then it could be mites
I could be wrong with my assessment.