Maples will sacrifice leaves here and there
during times of stress..
Heat, dry weather, not much food for it's roots, etc...
They will selectively choose leaves, to stop
feeding and they will dry up...
That is somewhat in the same process it takes
when turning to the fall colors too...

Your's look like its' just changing color for the season... Cooler nights and lighting *where the sun is* start the color changing
process for maples...and drier growing conditions.

Here's a bit more of the technical terms too.
Brief overview of a tree leaf during autumnal color change

* * * *
Weezie

Don't forget to be kind to strangers. For some who have
done this have entertained angels without realizing it.
- Bible - Hebrews 13:2





http://photobucket.com/albums/y250/weezie13/

It's been several weeks since we had rain here and everything is very dry now.... and i noticed some leaves falling from the maple tree in the front yard. I'm quite sure it's stress due to very dry conditions we are experiencing... ;-)

Dry weather is quite a change! Been a few years since i've seen it this dry.. .
Now i can see which plants in my garden are really drought resistant!! I'm not too worried since most have already have "done their thing" for the season and are deep rooted.

* * * *
Bob

I would just make sure to keep
watering it, every week until the
ground is frozen...

They like have adequate water until the
time they go to sleep.

* * * *
Weezie

Don't forget to be kind to strangers. For some who have
done this have entertained angels without realizing it.
- Bible - Hebrews 13:2





http://photobucket.com/albums/y250/weezie13/