Are you using a launcher other than default Samsung TouchWiz? I had this problem on Nova Launcher. So I uninstall it and reinstalled it. Since then, I had no issues. If you are on a custom launcher, try doing that.
No you don't have to be rooted to use a Launcher. But since you are default anyway... hum.... Try rebooting the phone. That's the only way I know how to reset the Samsung launcher.