I have had the temporary numbness on one side of my face, and also in arms and legs. When you cut off circulation, you cut off communication to nerves which is what causes the temporary numbness.
I have retrained myself over the years to make sure that when my body senses something needs to be moved or gotten off of while sleeping, that I partially wake up and change positions.
The only time you need to worry is if it happens even when you are not putting pressure on something or does not dissipate.
Lindaru