Just bought mine today, and yeah... it's pretty hot when plugged in. Google led me to this post...
I was updating and charging at the same time and heard a device disconnect sound, next thing I know the touch screen stopped working and I had to plug in a mouse to restart.
I also unplugged the charger. After restart, the touch screen worked again, so I'm not sure if it's overheating or driver update...
But anyway, I have it plugged in again now, and it's super hot. Not sure if it's safe to leave it plugged in?