I had a weird thing happen yesterday. I invoiced one of my regular customers on 3/30 and somehow managed (via eBay) to include on the invoice something he'd already gone through eBay checkout for and paid via PayPal on 3/27. I saw it when I did it but just didn't remember that he'd already paid for it.
So how is it that it showed up as unpaid for when I invoiced him for a newer win? Also, since he paid this new invoice (I refunded him later) the item shows that payment was received via PayPal on 3/30 (the second invoice). My PayPal account shows that he paid for the item on both dates.
I assume it was just a random glitch but FYI and all that...