Buyer left negative feedback two months after transaction

Hello all,

I've been a long time ebay member (since 1998) and just received my first negative feedback.  I'm asking for a little advice on how to handle it.  I sold a used item and the buyer left negative feedback seven weeks after the item was delivered.  The buyer made no attempt to contact me and I just happened to notice it when I was searching for a different item to purchase.  I just made an initial attempt to contact the buyer and am waiting on a reply.  Does anybody have any tips on what to do?

Thanks!