That's my default mode of storing the Karma (in its plugged-in cradle) and I haven't had any trouble with it yet.

There's only one issue with doing it that way. If you have the USB cable plugged into your PC, the Karma will boot up when you turn on the power to the PC. This is because the karma has to actually be on, with program code actively running, in order to respond to the PC's request for USB devices to identify themselves.

So if you want the Karma to stay turned off, unplug the USB cable when leaving it in the cradle.