here are a couple of pics.

Here is a link that might be useful: picture 1

here's a second pic

Here is a link that might be useful: picture 2

majortom,
I wouldn't be too concerned, especially with fall right around the corner. Photoperiod initiates fall colors, but when is subject to environmental stressors like water availability issues, nutrients, etc. they may come sooner. If it were July I'd be concerned. I assume that they were container grown. Correct?
If you suspect a micronutrient issue, give em a shot of kelp, diluted.
Good luck,
Noogy

hi Noogy. They were container grown. If it gets worse, I'll try the kelp. Thanks!