I don't think she can redo it. She could contact admin and see if they can reset it, but I'm not sure that they would. That is too bad. we should have the ability to edit our feedback for 30 seconds or something like we do when when post here.
I don't think you, or the buyer, should stress much over this. Your rating is still 100%, and very few buyers will start scrutinizing feedback comments of someone whose profile is 100%.
It simply looks like the buyer meant to type "thnks" and misspelled it.
I think you are right Debbie. She did check the positive first. I checked for the kiss and make up link that another post said should be under the feedback and there was none.
Oh well, if anyone reads my feedbacks.....it will be food for thought when they see the "Tht" sitting alone there.:)