I would not worry. probably a little shock from too much water, too little water, too much sun, to fast, too much fertilizer, too cold, too hot, or just adjusting. This is a symptom of an issue/reason from a week or more ago. As long as new growth is healthy, what5 happened in the past should not be a concern. In the parlance of the economists, leaves are a trailing indicator, showing the past, not a leading indicator predicting the future. My trees have had crummy looking leaves all summer, as we swung from 100F for a couple days, to 3-4 weeks of 70s, and back again. They yellowed, got black spots, fell off, got crispy edges, etc. As long as the growing tips were healthy - not to worry.