Why were two edits 29 sec apart not counted as a common edit?

Question

I noticed a few very minor formatting issues in Large(ish) finite non-abelian subgroups of $\operatorname{GL}_n \mathbb C$ for $n>70$ and, since it was on the front page, decided to fix them as edit 9. Then I noticed that I'd missed one, and went to revise my edit 9, but, although it was just 29 seconds later and so would usually be within the 5-minute grace period, it registered as edit 10. Does the 5-minute grace period not apply any more, or is there some other reason that this would have registered as two edits?

Answer 1

From the FAQ post "How does editing work?" (current revision)

During this period, any additional edits they make are collapsed into the same edit in the revision history, displaying only the final outcome of all their edits within that 5-minute period. The grace period ends after exactly 5 minutes, or if:

• Another user edits the post, at which time their grace period begins.
• A comment has been added to the post since the previous revision by anyone other than the editor (ignores deleted comments).
• The post being edited is a question and an answer has been added since the previous revision (ignores deleted answers but does include answers by the editor).
• The post is a question, and it has been closed since the previous revision.

I think that the second bullet point applies here. There was a comment between the two edits - as you can see on the timeline.

• Revision 9 has the timestamp 14:34:59Z.
• There is a comment with the timestamp 14:35:01Z.
• Revision 10 has the timestamp 14:35:26Z.

The comment might be deleted at some point - for posterity, I have posted the comment into MO editors' lounge; the timestamp should be visible there even if the comment is deleted.

Here is a related question on Mathematics Meta: Is the 5-minute grace period suddenly gone, or is it just me?