WHat was the glitch and was it your own fault?
it was an Etsy glitch. At first, it didn't show the usual confirmation of purchase--then it showed as not available. So she purchased similar listing, but not exactly the same.
I had already shipped both, so she chose the first preference and sent the other one back right away.
If it was a glitch of your own accord, I would say yes, refund it in good faith. If it was a Etsy Glitch and you talked to Support on Etsy.... tell them that due to the glith you are going to refund your customer the shipping they paid for; however, you would like it if Etsy you put some credit into your account that you can use towards your listing and other etsy fees to offset your shipping fee loss.
Thank you.
On my side expreriences have show me that refunding shipping charges she had to pay for sending back the item (even if it is not your mistake) was the best thing to do, this customer will appreciate 150% and will talk about your honnesty and how good seller you are, she "can" comeback and you will have more sales I can assure you.