Bump
I don't know. I don't grow it. I don't think that's normal.
I looked up its ancestry; it is a mixture of four species growing cool to hot, of which I've grown two. My impression is Brassias get lots of spots when humidity is low, the water has too many dissolved solids or it's too hot for them. Do any of those apply to your growing conditions?
They are susceptible to spider mites, but that damage looks different from this. It is more patchy and the spots would be even smaller.
By the way, most botanists have lumped Ada into Brassia, so this would now be called a Brassia.