Shortly after purchasing my 2012, I noticed that squealing noise too.
There is the usual sound of the fuel pump pressurizing the fuel rails, in the second immediately after switching on the ignition. But, then after the fuel pump is done doing it's thing, there's a persistent & continuous squealing sound cycling over & over. And it seems to vary slightly when you twist the throttle grip, right?
I went looking for the source with a stethoscope.
As others have noted already, the squealing sound is ultimately due to normal functioning of the TBW system.
On mine, I found it to be the stepper motor that controls the opening of the butterfly valves.
The stepper motor is located on the right-front of the throttle body assembly (from a seated rider's perspective).
The ECM is continuously making minor adjustments to the butterfly valve opening angle, based on the position of the throttle position sensor.
See the stepper motor annotated in the attached image.