Sometimes I think we get almost paranoid seeing spots, streaks, and other discolorations on our orchid leaves. I used to fret about every "abnormality" I saw, and with 100's of orchids, I saw a lot of them. I just remind myself that these are plants (often grown outdoors with Mother Nature, animals, and insects beating on them 24/7), and plants are not supposed to be "perfect".
If an orchid is growing well and appears otherwise healthy, I just don't worry about imperfections any longer. There are more than enough problems in this world to worry about.