Sales of 700 copies in one week spread over 464 stores is going to get any book pulled. That’s barely 1.5 books per U.S. location per week. With those numbers and limited space, I would pull it, too. Don’t read too much into it.
Something else to consider; Costco is closed on:
Easter
Memorial Day
Independence Day
Labor Day
Thanksgiving Day
Christmas
Costco also doesn’t have a problem with it’s employees wishing you a Merry Christmas or saying phrases such as “God bless you.”
Costco also pays its employee some of the highest wages in the retail business and provides good health care; at least before Obamacare.
But 700 copies in the first week is not bad if there is no advertising from the publisher.