Honestly,
I can see it from both sides.
As a seller, I HATE it when I sell something and then get bugged by the buyer without being provided with the time to actually ship. Some buyers get this ownership feeling of you when they send you money and feel the need to micromanage you. Dude might have felt like that was going to happened and cancelled the deal.
As a buyer, I can understand the excitement. In the future, you should provide the seller at least until the close of business to ship the package.
IMO the seller was a bit too sensitive and I've experienced a sensitive seller before and it stinks.
I remember getting a nice price on the Christmas Kobe 7s. I was excited so I posted I got a nice deal from a nter in the Kobe 7 thread at the time. The seller got mad and refunded me. I wasn't happy at all.
And PayPal gifts aren't worth it if you really don't know dude. That 2.9% is pennies at the end of the day when you consider piece of mind.