I've had this before, a few years ago, and a quick google at the time seemed to show that a fair few other people have. I'm in the UK, and about 6 months after buying something small from China (iirc), we got an £10 invoice for a "disbursement fee" from Fedex. It was very vague as to what the fee was actually for. I assume it was just a "scam" by Fedex to get more money.