I tried to post a comment on this answer and received the rather impersonal sounding reaction “User does not have permission to comment on this post”. I normally have no trouble posting comments and have seen no messages telling me about any changes to my permissions/privileges. My system (Firefox/Suse Linux) is running a little short of memory and when I refreshed the page and tried again it worked fine.
What is the background to this message and is there anything I should do about it?