eBay says "delivered left with individual" USPS says "forwarded".... which is it?

[filstreasurecollection]

Case opened against me today, item not received.  Buyer wants Full Refund.

I checked tracking on eBay, shows "delivered left with individual" Jan 06

I checked tracking on USPS, last comment shows "Your item was forwarded to a different address at 8:04 am on January 13, 2016 in Guttenburg, IA.  This was because of forwarding instructions or because the address or ZIP Code on the label was incorrect".

What do I do?  I checked the address on USPS, it seems valid.  I've seen on other threads where it's been stated that the forwarding message pops up when the post office makes a mistake, but I don't know, the buyer could've left forwarding information on their door or spoken directly to the carrier.  Because the buyer asked for Full Refund, I'm thinking that if they had done anything to cause the forward, they won't talk.  

Should I get involved and call the postoffice in Guttenburg - it's been 15 days now.  I'd like to find out where the item is, and not do the refund, because basically I've done my job and I don't want to lose out on the item and the money.  Again.  Last month I sent out a free replacement item when the initial shipment showed as "delivered", just to avoid a headache.