HBO? That doesn’t sound right. But it was. I guess it was either rerun on another channel, or it was on during one of those ubiquitous cable promos where you got HBO for 99 cents for 3 months then just $99.99 a month after that.

Because I know I saw the show, and we did not grow up with HBO.

Source: The Muppet article I linked to below, and wikipedia, which goes so far as to list all of the Fraggles, grouped into Primary and Secondary lists based on importance.