I've barely cried in my entire life and I hit day 3 and sat in a crowded hospital and bawled on the phone to my mother of all people, who I don't even like lol. The next day I was fine. They test here for PPD routinely and I aced every test with flying colors.
But it is serious so I would keep an eye on it. It never hurts to talk to a therapist or Doctor about it either. :-)