I got my EV plates!
Apparently I am the first person to receive these new EV plates in MA! The numbers on the plates correspond to different things such as when the registration needs renewal, which RMV they were assigned, etc. This was actually plate 7 out of the 10 this RMV that I could choose from and I liked the numbers. We had to call the main RMV office in Boston to get the supervisor, who said that this is the first time that she knew any of the EV plates were given out and even she had to figure out what to do with them.