I got an envelope like that today, too!! With my Hank Boss Chips. I can't help but think about the times that I've put extra postage on an envelope...the post office didn't say "you made a mistake and overpaid...here's a refund of the overage"

...and there was the time my brother taped 2 boxes together and sent them to me. "Somehow" they got cut apart in the postal system, and I had to pay the postage on one box that had already had the postage paid for!!

....and there was the envelope that was ripped open and no chips were inside it, but they didn't appear in the postal equivalent of the "lost & found"

NOT to start a legal debate, but what's "legal" and what's "right" don't always seem to be the same thing!