We're getting word from a tipster that beloved North Beach lunch counter/late-night-drunk-feast locale, Sam's Pizza and Burgers (618 Broadway), has been inexplicably closed at various times during the past two weeks. The phone is still connected, however no one is answering, and nearby workers who depend on those greasy, old-school cheeseburgers are understandably beside themselves. This may just be a temporary closure for all we know, but yes, there is cause for concern. File under: Developing. Update: They appear to still be open regularly at night, however daytime hours may not be as regular as they once were mid-week.