Baby poop!

Okay, so my son is a week old as of yesterday. He is formula fed. Pretty much ever since weve been home he poops after every feeding, but he went all day yesterday and that night without pooping which is not normal for him. He is eating well, stomach doesn’t seem hard. He isn’t overly fussy. I had to do the rectal thermometer early this morning to finally get him to poop, and it was still the proper consistency and wasn’t hard. Since I’ve done that this morning, he hasn’t pooped again today on his own. Has this happened to anyone else where their newborn just all of a sudden stopped pooping as much?