what type of maples? whats your temps been?

i would say a combination of transplant shock, shorter days and cooler temps.

Honestly, I'm not sure. I told him I wanted two red, two yellow, and two orange, but all turned red before they dropped leaves. He told me they were two sugar maple, two red maples, and two hybrid maples that I had never heard of. Temps right after they were planted were in the 60/70's day and 30/40's at night. The past few days have gotten closer to 80 with nights in the 50's.

I'm hoping it's not lack of water. I'd have to bucket brigade water them.

Best time to transplant is after the leaves have dropped.
Have you watered the tree? Trees drop leaves due to stress and lack of water.
Unless there was a long steady rain-- 2" the tree may not get adequate water down to the roots. Get out the buckets!

Water and mulch the tress.

30s-40s sounds about right for fall leave color change, plus its already october.

but if you're worried about it being too dry, get some bamboo skewers, stick them in the rootball for about a minute. pull them out. if the rootball is moist you'll feel some moisture on the bamboo skewers. if they come out dry, water lightly, b/c this late in the year they've probably gone dormant already.

Red Maples like their feet wet, Water them and water them well especially during the establishing period. I water my trees once a week for four hours on the full hose a ways back from the drip line to not mess up the soil and to get the full area wet. It's funny, the area gets saturated, I mean it's a lot of gallons of water(!), but by the time I've put the hose on the tree next to it and walked back, the water has already sunk into the ground, completely disappeared.That's my sandy soil for you. It is literally impossible to over water trees here.

Anyway, I do that once a week and my red maples are doing outstanding, no transplant shock occurred at all. And my October glory that I planted 2 years ago grew 2 1/2 feet this spring and summer. My Red Sunsets grew just less than a foot, but that is because they've only been in the ground 11 1/2 months. None of them dropped leaves early and that is because I kept them well watered. That is basically transplant shock, a tree that is not getting enough water during that critical period following transplanting. Of course it also depends on your soil type. I have sandy loam that is super fast draining.