Did they not charge b/c you are a Platinum or something else.

I am not a Platinum and am in a similar situation with (United) award ticket - did not have the doc at ticketing time and now I do, but when I
call to change they say cough up $100.

I did a search on name change in the flyertalk froum; others have reported success with just leaving the old name on the ticket but provide documentation at boarding time about the old and new name and being able to get away w/o paying the fee.