In the case of the OP’s coin they won’t do anything unless you want to pay for Reholder fee. They will change the description to their current SP designation. Your slab doesn’t meet the requirement of a mechanical error since the designation on the label was their terminology used at the time for SMS coins.
I believe you should call customer service and ask if a paid membership is needed in order to send a coin in for a mechanical error correction on a coin you purchased in that condition. With new management now in place customer service may be more user friendly. You might also get a knowledgeable reply by posting the question on the CU message board........it is free. Many times as of late management personnel will post an answer.
Every thread is a numismatic riddle. We like to address all tangential issues and even completely unrelated issues, saving the best post for last (i.e. the actual answer). Are you confused yet?