"Not Permitted" error on page refresh using Collab Editing

I have a space called "Lars", with a page called "Collab"

I log in to confluence, and edit the page:
http://documentation.example.com/pages/resumedraft.action?draftId=6652144&draftShareId=cf4a941e-b40c-4149-a30f-5d1e6c10b67c

If i hit F5 (refresh) i get "Not Permitted" and the url changes
http://documentation.example.com/pages/editpage.action?useDraft=true&spaceKey=LARS&draftId=6652144&pageId=6652143

Pressing back, lets me choose edit the page one again. It will let me save. My user is also member of confluence-administrators