September 7 seems late. Yes, I invariably think of Labor Day as falling around September 3 or 4. BUT, it can fall from September 1 to September 7. It can’t be any earlier or later. First Monday of September. So, 1 to 7.
It fell on September 7 just 5-years ago. Yes, in 2015.
Also in 2009. So, this is the 3rd time since 2020.
The usual gap is 5- or 6-years. Then Leap Years kick in and throw it off for a 11-year gap. Those 11-year gaps are common in calendaring. It has to do with the 4-years between Leap Years & the 7 days in a week.
September 7 is not an anomaly. It happens quite often. 9 times in the last 56-years. That is an average of every 6.2-years.