Answer: What you describe sounds like maple leaf gall or bladder gall, the result of a mite feeding on the leaf. The galls are not harmful to the leaves of your tree and the mites have already done their damage and have left the area. Aside from looking strange, your sugar maple will be just fine. Some years you'll see more galls than other years. There's nothing you can do at this stage, so don't be too concerned about the leaves of your tree. Best wishes with your landscape!
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