Your problem sounds more complicated than what you describe. More information and adding some pictures would help those reading this visualize the situation.

Have you been watering the tree up until you worked on the mulch problem? Working on a stressed tree where you might have broken surface roots with the rake could explain the wilting.

How much top soil did you add to the surface of the mound? It would take more than a couple inches of dirt to smother roots imo.

How deep is the mulch? You only need 2-3" on top, to protect the soil from the hot sun and hold moisture.

I personally would be hesitant using freshly ground mulch, unless I knew it was completely dead wood and bark. Heaping stuff on that contains green or sap wood, could result in various gases given off as it breaks down, at least for the first week or two.

Did you water it good after you were finished? And continue to water as needed afterwards? If it's been really hot and dry there as you describe, anything that upsets the tree could cause it to react and show signs of stress.

Thanks GG! I wasn't sure about how much soil it would take to smother roots. We have such a grainy, gravely soil here that drains quickly and I really can't recall if I every done that before. :-)

But yes, if the OP was trying to level the ground with a rake that could've upset the surface roots and from what I've seen with my new Acer Saccharum, it doesn't take much to throw them into a tizzy. Although mine has shown to be quite resilient and has recovered from more than one abusive gesture on my part, so I wouldn't worry about it, just keep it watered as needed and I'm sure it will be fine. :-)

More info. 3 inches mulch. I watered but after I had finished. However I did everything in a short period of time. This all happened quickly. Don't believe I would have damaged surface roots too much as I pulled away old mulch by hand. Perhaps the bare surface was open a bit too long in the hot afternoon before I watered? THe damage was so sudden after my work I assumed my changes must have done it. I felt as though I looked away and back and a branch was fried with other spots shriveling.

Yes, hot sun on bare soil can quickly raise temperature to the point it can actually 'cook' the roots. The finer roots will get damaged first. Hopefully yours were not damaged all that deep but just enough to cause some wilting. Your tree has been in the ground long enough, it should have a well established root system with good range and will shrug this off in a few weeks. The undamaged parts of the tree may continue to grow even before that, which would be a good sign.

If I recall correctly, you have a nice clay loam soil right? Acer Saccharums grows good in those types of soil so you should end up with a beautiful tree in a few years.

Let us know how this one turns out in a few weeks. :^)

Thanks Bill and Gardengal. I was rather annoyed with myself yesterday. Lesson learned. The Maple this season finally had put out a vigorous little canopy looking like it wants to become a real tree and then I thought I went and killed it. I'll keep my fingers crossed. And yes, clay loam.