I waited to post this, until I become sure about it.
The skill points changes over time!!!
Beside, i uses a maxLevel mod wich allow to grow until 100 and I am playing single mode on PC.
What happens is: My attributes are changing without any reason over time. I realized this when my health does not recover. It is not much, but since I adjust typically to a skill-node, it become obvious. It might be due to the ccmaxLevel mod but I dont dare to uninstall this while loosing my skills.