You're right, it's a minor debris filled die error. Grease filled die is a long standing term in the hobby, but technically the devices can be filled with anything, so using debris filled die or filled die is probably more accurate, but generally, you'll find the terms interchangeable
I know from the condition it is in that it is only worth face value, but wanted to know the term for it because I saw a error coin missing the T in trust, but not the GO in God!
Now just come up with a catchy name and it will fetch big bucks on the 'bay !! Hows about- the General Motors quarter ??