Electrical resistance will make your voltage drop.
There is some resistance in a talon, but not that much. This particular talon could be a bad one though, with a greater resistance.
Wire has resistance as well. If you have long wire runs, the voltage could easily drop to 8v by the time it reaches the motor. This calculator shows you how severe that effect may be.
http://www.calculator.net/voltage-drop-calculator.html
There could be a loose or badly terminated wire somewhere along the path. This would increase resistance, further lowering voltage.
Also, it is possible the value you get is what the current battery voltage is. These batteries don't always output 12v, but I'm sure you knew that.
It could also be that your voltmeter isn't great, or has poor connections.
If the lights on the talons are flashing as you press the button, I'd think it was code. if their not, its probably something else.
Your code looks correct, assuming it runs every loop.