Update Drupal core via Pantheon I push all my local changes to the Pantheon git repository, then I update core via the pantheon dashboard. Now I pull from the Pantheon repository with "git pull git://github.com/pantheon-systems/drops-7.git master"
I am assuming that both versions are identical now, however, when I run git status I get a message that my branch is ahead of origin/master.

Can somebody explain this to me and how I get the local and repository in synch?
Yes that makes perfect sense - you've merged changes from the core repo, so your working copy is one commit ahead of your site's dev repo on Pantheon. Note that origin/master refers to the remote representing your repo, not drops-7.git

git push


to send the changes up to your dev site when you're ready to test, then pull them through the dashboard as normal.