hook_civicrm_post is called either once or twice for contact add/remove group depending where you make change

Here is how to recreate...

Go to the summary page of an Individual Contact.
Now click EDIT, and then scroll down and click on the Tags and Groups section and then check any group to add the individual and click save.
This will make TWO separate calls to hook_civicrm_post ... one for Edit Individual and the other for Create GroupContact.

Now go back to summary page, and click on the Group TAB at the top.
Choose a group from the select box and click ADD.
This will make only ONE call to hook_civicrm_post for the Create GroupContact only.

Not sure which one is the bug, but it seems to me that even when an Individual is added to a Group (via Group TAB), that it should also call the hook for the Edit Inidividual as well.

Thanks