Sorry,I don't understand. If you have only five minutes to edit and then it marks the post edited, why was there 'No marker saying this post edited' when you edited post from September? Oh dear! How convoluted a sentence was that?You have five minutes to make a correction, before the system marks the post as edited.
After that, I think you can edit upto a year later.
Just checked and I can edit a post from last September.
No marker saying this post edited.
P.S. I feel like I've entered an virtual reality, where things might be or might not be as they were, and where I can change what I've done (wish it were so in real-life)...