The spots do not seem to be normal... it looks now to be some sort of fungus that is airborne spread... I have a feeling that if those spots are left alone, they will turn brownish and mushy... eventually, the plant (if left that way) will die.
There are some spots that are naturally occuring in Oncidiinae, but do not look like that... they are usually more subtle and often times black. Also, it is spreading from an Oncidiinae to a Pleurothallid, so I assume that it is a serious problem... I would advise splitting the good unaffected plants from the affected ones immediately to prevent further possible devestation... after the problem is resolved (completely, it may take a month), then increase the growing area's air circulation... good luck =)
-Pat
|