hmmmm..... Not sure if I ever noticed the trademark before.
"The ® registered trademark symbol (known as the “Circle R”) conveys a very important meaning. The registered trademark symbol signifies that a trademark or service mark has been federally registered with the United States Patent and Trademark Office (USPTO). It’s regularly used by owners of registered trademarks TO PUT THE WORLD ON ACTUAL NOTICE of their federal trademark rights and to deter others who may be considering adopting an identical or confusingly similar mark."