This happened to me too when I went to renew my boat registration.
I called DOL, their explanation was some boats VIN (HIN) numbers don't meet Coast Guard criteria. I asked then to explain what was wrong with my current number, and they said that one of the twelve characters was a letter when it should have been a number, so it was non-conforming.
I figured the lady on the phone was simply earning a paycheck so I didn't cuss her out, even though my mind was circling around the b.s. of this ridiculous change. I have had this boat registered in Washington for the past 25 years, and now suddenly I have to have new HIN plates made and attach them to the boat!?!?!?
I considered writing a letter to the Commandant of the Coast Guard in Washington D.C., explaining the stupidity of this rule, and how much it will cost me to conform to Washington states interpretation of their rules. I suspect someone is overzealous, wearing their panties too tight, or both. Ultimately I figured I am too old and tired for this fight, and will simply bite the bullet.
Another example of bureaucracy run amok!