I have a few things to say about this... First, we all know you didn't really "tow it" to a shop. You drove it there, we get it. This nameless shop, Reputable or not, they're just people, and they make mistakes just like everyone else. These mistakes are more common in gear installs than just about anything else. I have personally installed nearly 50 gear sets over the years, many of them included a new, or used, carrier of some sort. I've never, not once, seen a warped carrier. Not saying it's impossible, just saying it's not likely. I've had to correct a bad install of my own a couple times, and I would have loved to have blamed it on a bad carrier or gears, but I couldn't. The carrier in question is a takeout from a brand new car, and was one of many taken out to have Torsen diffs installed in the FR500S racecars at Miller Motorsports Park. That diff, when removed, was in perfect working order. These carriers are pretty robust and just sitting in a box isn't going to alter them in any way either. It's possible the unit could have been dropped which has the potential to damage the unit. It's possible it was just a bad install (a warped carrier should have been caught by the installer). With these possibilities in mind, there really isn't anyone to blame.