I know this is an old thread but after doing some digging I've found that this is nothing more than a clever marketing ploy on tinder's part and
wanted to share in case this was still a mystoy for you. The star is the symbol used for tinder's "superlike" button, to show people on the app you
more than just like them. One of the adds even says introducing superlike presented by tinder. Nothing more then tinder being clever.