Keep looking, some scale hide under leaves, usually when they are young and they look different. They can also come from the soil.
If you don't watch for them you can find yourself with a bad infestation. I've had Camellia scale for years and spent a lot of time manually removing them, they can appear most of the year in milder conditions. Some scale have predators, I had a different type on a Holly tree but they got eaten by something, some ladybugs eat scale. This year I have had very few scale on Camellias, it seems something is eating them. Lacewing larvae eat some scale too.
