[tei-council] stylesheets repo permissions

I wanted to make a minor change to a file in the Stylesheets tree (specifically profiles/tei/slides/to.xsl) I connected to the github site using https, and logging in as lb42. For some reason, although I can open the required file for editing and make the change, the button to commit the change is grayed out. This doesnt happen with other files in the same tree (e.g. the Readme) so what's the deal here?