Sorry James, but being completely impartial and looking at it from both sides, did either of you contact each other after the auction? Ebay rules do stipulate that the buyer and seller should contact each other 3 days after the auction closes.
On the other hand, if he played by the book, he should have just filed an Unpaid Item Dispute, if he was that concerned. He shouldn't have left you a neg until after trying to sort it out with you directly.
I know I sound a bit hypocritical after my last Ebay escapade, so forgive me. Good news BTW - the neg was removed, and I now have a 100% positive feedback count again!