Answer: Your spring weather may have something to do with the coloring of the leaves--the hot, dry weather could have stressed the trees. I would be more concerned about the tree not leafing out fully. Has the weather stabilized--have you gotten plenty of water recently? Sometimes heat and water stress, by themselves, won't harm a tree significantly, but they can weaken it to a point where pests can cause damage. If you have not had rain, I suggest you water the tree very deeply and fully, preferably with a soaker hose or by letting water trickle from a hose. Maple roots tend to be relatively shallow, and cover a large surface area, so try to be sure the soil is moistened deeply out to the tree's drip line. (Hopefully, mother nature has done this for you already.)
Since this sounds like a spectacular, and special, tree, it might be a good idea to consult with a local arborist or other tree specialist, just to be sure you don't have an insect or disease problem.
Q&A Library Searching Tips