Max's special pooping spot

I honestly can't remember the last time we took Max to our local Barnes and Noble and Max DIDN'T poop. We go about once a week, mainly just to browse the books and let Max play with the train they there. But for whatever reason, every time we go there, Max ends up pooping. He only makes one poop a day and he is sort of irregular about when it happens, so that's why it is fascinating to me that no matter what time of day we go to the bookstore, he ends up pooping.