Newbie seller

I've sold some audio equipment for the first time and am a little perplexed at what is happening.  Would appreciate comments so I can avoid problems again.

First time out was intentionally low risk: Schiit Modi 3 and Vali 2 for $175 on US Audio.  PayPal, buyer pays shipping.  Insurance was through US Audio's recommended 3rd party insurer.  Original packaging, plenty of pictures. 

I was immediately contacted by a guy in Portland.  He has about 25 purchases on record at USAudio, mostly of Schiit products.  Good seller comments.  I issued the invoice and he paid via PayPal.  However, because I am a first time seller PayPal put a hold on the funds pending proof of delivery.

Next day 6/23 I shipped via USPS parcel select, adult signature required.  Tracking shows item got to Portland 6/29, moved around Portland USPS facilities until 7/2, then nothing.  Never even went out for delivery. 

To my surprise on 7/15 PayPal released the funds to my account.  I filed a missing package form with USPS but they haven't found the package.  Can't submit an insurance claim until 7/23 (30 days).  Not a peep from the buyer! 

I'm perplexed at that.  I plan on filing an insurance claim on Saturday, even though I have the money.  As I understand it the buyer has plenty of time to file a claim with PayPal saying he never got delivery, and rightly so.  Would you guys have done things differently?  There's not much at stake here, but if I sell (or buy) anything of substantial value I want to do it right and minimize my risk.  Comments are appreciated.