Rebasing locally before "publishing" (pushing) changes to the central repo is definitely okay. It should always be done before pushing the branch for the first time, really, because if someone else has modified develop since you started your branch, you want to make sure your changes are still working and won't break the build (on develop).

You're right, it's not. I need to stop commenting on HN before I've had coffee. :/

Is there a link where I can read up the type of Git flow that you are talking about?