In my experience, they almost always make errors in rating PA/RA under 5002. Most often, they fail to rate on minimum ratings on chronic residuals. These cases are very difficult to win without help. If you have joint pain in multiple joints, either constantly or on flares, you might look for some outside help on this. Again, they are hard to win at the PEB, but can be won on appeal.
This issue is one of the most glaring errors at the PEBs (across all services). maparker can give some more insight as he is well versed in these issues, too.
Seems like you should appeal. Little to lose and much to gain. Good luck!