Not saying this is a 100% accurate, just relaying what a guy who has been in the fruit tree business for 30+ years just told me. He said when those small leaves appear like that, but remain green it could very well be a Zinc deficiency. Symptoms are normally on all leaves though. A soil test which includes Zinc level can help rule it out. He also told me that Zinc deficiency in a tree cannot be corrected long term by a foliar micro nutrient spray only, as the Zinc remains mostly in the leaves and is not absorbed back into the "system".
However, when the leaves appear (like those in your picture and what I have at my house) and then get brown edges and eventually die back that is likely the result of some herbicide uptake the PREVIOUS year. Can even be Roundup drift from the year before. He says a young tree will pull that herbicide drift into the root system and then it will get pushed back to the leaves in the spring. Most of the time on larger trees it will only be apparent on the lowest branches.