A huge police union in Las Vegas is beefing with the NFL over one of its new credentialing policies ... and if the matter doesn't get sorted out soon -- it could mean big headaches are on the horizon for the Raiders. According to Steve Grammas -- the president of the Las Vegas Police Protective Association -- Roger Goodell's org. has implemented a new series of protocols for police members working games this season ... and Grammas says he's got issues with them.