It looks as if there was a rejected match that day. That may be the last "modification" that was recorded.
None of the below will show in the changes tab but will be recorded as a modification.
* If an attached photo has a new comment or edit.
* If a person's marriage is edited via their spouse.
* If a merge status is changed, or a rejected match is added.
* Privacy Level changes.
* Profile Manager changes, if done in bulk or indirectly.
* If a DNA test is added for the person.
* If a badge is awarded to the person.
