The raccoons might have been growling at Portia rather than me. I see them on the back porch frequently, as they raid the feral cats' food bowls, and they see me through the window but never growl. I've never heard them growl at the feral cats, on those rare occasions when they've seen one another, but then the feral cats are gray. Maybe the raccoons just don't like black and white kitties such as Portia, because they sort of resemble skunks. Raccoons are not big fans of skunks.