Agreed. I've also been having this problem for a while.
It's ridiculous. This is my third surface pro 2 and I've had issues with all of them. This one is by far one of the most annoying. I've noticed it gets worse after updates - that's when I notice more restarts.
I've had it happen when bending the type cover back, but also just when moving or picking up the tablet. At times it's unusable. Once the darned thing restarted THREE times in a row - it didn't even get past the Surface logo without doing it. Shame. It seems like with Surface, you always have to be weary of updates. *rolls eyes*