USPS package - mailman signed for it?

[ValKehl]

I live on the 3rd floor of a keypad-access seniors condo building. Ever since my wife and I moved here 1.5 years ago, I have striven to achieve a friendly relationship with our mail carrier, who is a nice guy, especially because we ship stuff we sell on eBay, and we very frequently leave our outgoing packages on the floor at the base of our building's bank of mailboxes for him to pick up and take with him.

Well, today, our doorbell rings, and it's our mail carrier with a package for me to sign for - a $600+ card I just won on eBay. As I was signing the signature card, this carrier casually mentioned that he had signed a shipment for me recently and left it in my mailbox so as to save me a trip to the Post Office to pick it up. It immediately entered my mind that this is totally inappropriate, and probably illegal as well. What to do/say? I made the instantaneous decision to smile and thank him for his thoughtfulness, as opposed to expressing my displeasure. As soon as he left, I remembered the package containing a similarly pricey bb card that I found in my mailbox a week or two ago; and I remembered being surprised at that time that I hadn't been required to sign for it; but, it didn't dawn on me that my mail carrier had signed for me - rather, I assumed the shipper didn't take the necessary action to require a signature upon delivery. Upon further reflection, I've decided I'm ok with my carrier doing this, despite the extra risk involved - but, I would feel differently if I didn't have a good relationship with this carrier.
Val