Looking at the deal, there are signatures (although the signed page is different here--why?). But it looks more like a "from all of us" greeting card than a formal diplomatic document, no?
Where are the neatly aligned signatures? The official wax seals? Where are the ribbons, for Pete's sake, that elevate a mere piece of paper containing words that might be your "to do list" affixed to your refrigerator door with magnets, into an actual formal deal between nations?
Of course, there is a reason that Wikipedia labels this JCPOA title page as "souvenir signatures." The "signed" deal is no such thing, as the State Department confirmed.
The relevant part of the letter states:
The Joint Comprehensive Plan of Action (JCPOA) is not a treaty or an executive agreement, and is not a signed document.
So basically it is a document that everybody agreed to pick up and take home.
So yeah, this was just a Bizarro World Hallmark moment to mark the occasion of giving gifts to Iran.