@"Cant Get Right" thats an interesting way to study. I am not going to lie, when I see I made a careless mistake, I just move on and say I need to pay more attention without giving it more thought. But I will definitely take your advice!
No, do not write an addendum for this. You'll just be drawing way too much undue attention for a minuscule difference. It will just be another thing for an adcom to read without adding value which is something to avoid.
LOL thanks for the edit, @"Dillon A. Wright" , I was in fact joking...unless I suffer from multiple-personality disorder and that edit was actually made by my second (more serious, less friendly, possibly more attractive) persona. Yawza.