Usually edits made within 5 minutes of making or editing a post are rolled into a single revision in the edit history. However, it looks like edits are getting listed separately even if they were within the grace period.
This is a regression. We're working on restoring the proper grace period edit functionality and will update here once complete.
Update: Grace period edits have been restored. I was hoping it would have been released quick enough for me to have a grace period edit, but alas my punishment is another revision on this answer. Apologies for the inconvenience.