New surface pro getting really hot while charging

Hey all,

Is it normal that every time I charge my new sp i7 16gb it gets really hot on the back even when it is in sleep mode?

I was using it for like 2 hours and it was completely cool but now I put it to charge and in sleep mode and it gets really hot quickly. That's strange and worries me a bit

Yesterday during first usage I was charging it as well and was surprised how hot it got.