It woudn't revert on the top. The only unusual growth would be below the graft. Stunted growth can be a sign on nutrient deficiency, or lack enough water, but it could be normal. Did you plant it this year?

Late season growth on any number of cultivars of JM's can produce foliage that looks quite different. CCJ is known for producing very narrow, spiky leaves with a late season growth spurt. Nothing to be concerned about and next year's foliage will look as it should........unless it decides to do it again ;-))

I planted it 3 years ago. I don't remember seeing any unusual foliage in past years. I have other JM's in the vicinity and they are doing ok. I guess I will do nothing. Thanks.

"I guess I will do nothing. "

It begs to be asked.......what would you contemplate doing? Cutting it all off??

There is really nothing wrong with your tree and the foliage growth next spring should be normal. Japanese maples will often throw out branches with divergent foliage, it is really NBD unless it is a solid green shoot on a variegated cultivar or unless it is coming from the rootstock and not the scion. Both of those situations demand removal. But not in this case.