I think they will stand behind their work...it's just the cost/inconvenience to you. That should have been an easy fix.
I'm leery to have anything altered at my Nordies. (HOuston) One of my first premium denim purchases was the COH Avas. I told the alterations person that I wanted plenty of scrunch. They came back too short to even wear with flats. At that time I was too timid to go back. Everytime I see those jeans, I wish I had. (Coincidentally, they're going to resale today.)
More recently, I had the sleeves shortened on my Theory Lanai jacket. It took 3 times to get the sleeves the same length. Frustration!
I bought the Burberry peacoat at NAS and I still haven't taken it in to have the sleeves shortened. I need to have Nordies do it to be protected if they ruin it. However, I don't have confidence that it will be done properly. I love the coat and want it to work..I believe it's sold out so no replacing if ruined.
Sorry to turn this into a rant, but I hear your frustration. Nordies is so good in so many areas and I wish the alterations department was included in that.
As a solution, do you have a local tailor that could move the button for you? I wouldn't think it would cost more that $5..less than the toll back to Nordies. Do let Nordies know, they can't fix things (shoddy alterations) they don't know about.