From applications manager clear the cache for TouchWiz. If the issue persists then clean the phone cache through the recovery manager (phone off, use power, home and volume up button to enter recovery then wipe cache. This will not delete data)
Don't worry,between a note 3,s5 and now back on an s4,I've seen this message more times than I would hope. All it'll ever do is react a little slower when you tap the home button,since it needs to reload.