Someone trying to scam me on eBay. Help me out please

[needsomejays]

Posting on mobile so bear with me.
Post a pair of jordans for sale for a buy it now option only. Get noticed within an hour they were sold and the guy sent the payment immediately(July 11th). I sent the shoes out that following Monday(the 13th) via USPS priority mail. I also printed the label right from eBay/PayPal, so all the tracking is automatically on there.
Dude messages me today saying he just got back from vacation and the shoes weren't there. Says he went to the post office and they didn't have them either. Now they opened a claim on me. I took all the money out of my PayPal account as a precautionary measure so I don't get screwed over.
What else should I do about this?

Forgot to add, it was shipped to a PO box, meaning they had to go pick it up. The tracking clearly says when the item was picked up

 

[airthompson]

You have proof they sent, and I'm assuming buyer didnt ask for insurance. All you can do is hamg tight. Ebay is horrible with seller protection. Sell locally in the future.

 

[verbal kint]

If you didnt get signature tracking, you might be hoooosed

 

[ryda421]

well when people learn to do signature. for a couple more bucks you could have prevented this but instead you go the cheap route