I guess even a microscopic burr would cause this.
Yep. I won't say it's easily fixed but it can be. A sharp exacto No11 can be scraped around the port edges to remove any wire edge that happens to be there. I have done this with great success, but other times, particularly when the damage is from the Cox spanner, it can be difficult to clean up. It's still quite fixable though, just can take time.
Luke.