I had no reason to believe the scale was wrong and I don't own a scale myself. The post office I go to is a small one and the guy there has looked out for me for years. I don't think it was him being dishonest but honestly most of the USPS equipment is so ancient I probably should have thought more of it.
I almost always ship flat rate but in this case the flat rate box that this pcb fit was fixed at $60 so when it came up to that number I just figured it was right. Lesson learned. I'll buy a scale before the next time I ship internationally. USPS really is the best deal for most shipping. Especially domestically. But the international shipping has gotten more expensive and there are fewer options for us now. For example, everything that is considered a parcel has to be shipped with the Priority rate. But if you can fit it in a shipping envelope it can be shipped at the letter rate.
Regardless, the scale was very wrong and we got screwed. And as bad as the USPS is bleeding money I wouldn't be surprised if it was on purpose. It's another example of the labor unions doing more harm than good now. They have outlived their usefulness.
My apologies to you, Silverfox, for screwing the shipping up. I hope the pcb works well for you at least.