I wrote back and said, "I gave you my office physical address in San Mateo CA, per the attached message. Where did you ship it?"
He replied that what eBay had sent him pointed to the PO Box in Mehama, and that's where it went.
The Mehama address is the default, since nearly everything I buy on eBay goes there, but for the seller to see a different address than the buyer is kind of odd. It's not a big deal; I was just accumulating spare parts for the computers because now that Dell has discontinued the Inspiron 600m, I expect to see the supply of parts dry up soon, given that Dell seems to think they need to completely retool every six months or so *sigh*. I don't need the part right away and will get it on my next trip north.
But the next time I buy something through eBay and want it shipped anywhere but the default address, I think I'll be more insistent upon the address, putting it in the comment fields as well as setting the various toggles in the eBay/PayPal process.