Well, the elusive creature has not been back.
I wanted Ted (just Ted since I 'guilted' TedandHolly into getting their own user names) to come visit and try to figure what it was.
I think it was something in the ferret/weasel/mink family, and I have a disposible camera at the counter by the back door so I can snap it if it shows up again.
DH still thinks it was a feral cat, and that I was losing my mind. lol