Yes, this has been reported on here. I arrive at my reservations 15 minutes before as instructed. This is one of the reason people have to wait for their reservations....people show up late or show up early hoping to get seated early (even though there were no reservations for an earlier time when they booked). I know sometimes people show up late due to reasons beyond their control.
Bottom line, show up when your actual reservation is and there shouldn't be a problem. But, always check your credit card statements to ensure there are no unauthorized charges on there. This holds true for everything, not just WDW.