The Israelis often/always put the official date of issue/printing in the selvage so I assume that's what this is.
In most cases, the date on the sheet margins is the date the stamps rolled off the press, and not the date of issue. Some stamps can be seen printed many months earlier than issue date.
I would guess the same can be said of this French block. If someone has a specialized, or semi-specialized French catalogue, we can found out the truth !!