Hydrometer or Murphy cup could be slightly off anyways. I remember a study from Dr. Tim that showed how far off they can be. I have multiple SmokyLake gold vermont certified hydrometers and a murphy cup and they all read slightly different from each other. Some are off by nearly 3/4 brix (and no, the paper hasn't slid as these come with the red line to show that). I have cross checked them with a calibrated optical refractometer and digital Misco refractomer countless times.

Being over by 0.5 brix for your own consumption is not going to be a big deal. In fact, given the accuracy and error of these instruments, I'd rather read a touch heavy and ensure it's actually over 66 Brix.