Answer: If there's a shiny or sticky substance on the leaves and they are wrinkled and distorted, I suspect there's an insect population. Aphids, scales and mealybugs pierce the leaves and feed on the fluids. This causes off-color, wrinkled leaves with a sticky substance called honeydew. Unfurl the affected leaves. I think you'll find insects feeding. The control depends upon the insect. If you can't identify the pest, take a few of the leaves (in a plastic bag) to your local nursery. Helpful folks there will identify the pests and provide control options.
Best wishes with your lemon tree!
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