If you do get a neg, you can respond with a follow up comment that addresses it i.e. Measurements provided, full refund issued or whatever is most pertinent to her feedback comment. Hope you do not get one, but prospective buyers will, if they see the neg, see your comment and it should be fine.

I have bought from sellers with the odd neg where otherwise they have a good record, if it looks like it was the buyer that caused any situation.

Kopenhagen is right about the possibility it has been worn, too; you really need to wait to see it before a refund.