According to the following document: https://cloud.google.com/container-engine/docs/clusters/upgrade Google is managing the container cluster master - which they are rolling out new version of kubernetes. I've noticed that the current version on our system is 1.6.10-gke.1 - do you know is i should upgrade myself?
The master is automatically upgraded as described at the bottom of that page. It isn't upgraded immediately, so that there is time for tests and staged rollouts.