There are a variety of gall forming insects that will cause plant leaves to develop bumps on the leaf surface. Sometimes they are a variety of colors, different size and sometimes wierd shapes. The gall insect is usually a very tiny wasp like insect. Because they really cause no major damage to the plant short of making is look bad and if you spray with anything right now yo will be wasting your time, we suggest that you do nothing. The plant will be fine only just look bad. Even preventitive sprays are not suggested as the time is so very critical that you would miss it anyhow.