Today, at 12 weeks old, Augie decided he's bored with laying on his back and wants to grunt and squirm and roll his way over on to his tummy. He's done it four times today! Apparently back-to-tummy rolling isn't supposed to happen until ohhh, around 5-7 months?? We were already vigilant with him on high surfaces but now we'll be extra cautious and do things like belt him on the change table, etc.
It's not really surprising considering he rolled around so much in utero that he tied a knot in his umbilical cord. I later read a true knot like that happens in less that 1% of pregnancies.