Maille mustard-different?

Thanks all. I still think there's something up, but who knows.

Mustard loses pungency rapidly over time, even when unopened. It could be that the formula is the same and you just got a particularly "young" jar.

Maille makes various kinds of mustard--perhaps you bought one with horseradish or something else added.

Most Maille mustard sold in the US is from Canada, and it is much milder than what's sold in Europe. A shame in my book.

Doesn't Maille mustard require a European Union PDO designation (Protected Designation of Origin)? For shame, I do not have a jar in my fridge right now to check.

Yes and no. Don't know about different states, but many companies European companies manufacture differently for the US than other parts of the world due to the American tastes: more sugar, more salt. Also labelling requirements. This should not be a surprise as Maille is now owned by Unilever !
Perhaps you ended up buying a jar that was stale-dated.
Try locating a jar in a European deli that says made in France on the label. That will most likely have the European formula rather than the US market formula.