I just had this VERY thing happen to me. I won an auction, paid immediately and the RECEIVED the item. Last night I got an email from the seller asking me why they hadn't been paid for the item.
I went into my Paypal account and sure enough there was the payment sitting there "unclaimed." I emailed the seller back and told her to contact ebay to find out what to do. She didn't reply, but this morning I woke up to a NON-PAY COMPLAINT filed against me!
I immediately called PayPal. They removed the non-pay complaint and told me that the seller had inserted the wrong email address into her Paypal account so when I paid, the money couldn't go anywhere. So I had to cancel, have her send me an invoice and repay.
Why not just communicate this to me instead of file a claim?
Just goes to show you though....be careful about entering your email address into your Paypal account. If you enter a wrong address and it is a working address, someone else might get your money.