Spray with a good fungicide. Catts (whose growths and leaves can last for years) are going to show these signs of aging as they mature, much as people develop lines and wrinkles. If you look at the folliage of superb, award-winning plants, you will notice the same kind of spotting and blotching. I suppose this kind of thing is preventable if you grow your plants in some kind of antiseptic bubble, but that's pretty unrealistic. The foliage of most plants in the wild looks absolutely horrendous, and as a general rule, orchids are not grown for the appearance of their folliage.
Spots like these are typically fungus-related: get yourself any kind of "disease-control" stuff that's formulated for ornamentals from your local box store, mix according to directions, and spray once every month to month-and-a-half. That will help prevent this kind of blotching from cropping up.
(Your plant is fine....)