Sorry for 3 months old bump, but I've got a response from Motorola and saw this thread.
X: Hi, my name is X. How may I help you?
(unknown): Hello, my name is [Me]. I want to ask you a question about Moto G.
X: Hello, [Me]. I will be more than happy to assist you on this.
(unknown): I used CPU-Z to look at a few details about Moto G's hardware and noticed that the battery voltage is 4.3V when fully charged. Is this normal?
(unknown): I've read on the internet that Li-Ion batteries shouldn't exceed 4.2v
X: Let me check on my resources. Please hold on.
(unknown): Thank you.
X: No problem. Do you already have our Moto G or you're planning to buy one?
(unknown): I already have one, just checked the voltage with an app (the default android hardware info menu has the same values so it's correct) and I was wondering if it's a bad thing.
(unknown): Is Moto G's battery of higher quality?
X: Okay and yes, it is.
I said something about higher quality because I read this: learn.adafruit.com/li-ion-and-lipoly-batteries/voltages
"Nowadays you may also be able to purchase 4.35V cells! These are the latest chemistry, they have a little more power as indicated by the voltage being higher than 4.2V. They tend to be cylinder lithium ion's used for laptop batteries, and lights so its not terribly likely you'll just run into one unless you're looking for it."
So does this mean we shouldn't worry about it?