Thanks, hawaiian traveler (and apologies to all for my part in getting this thread off on a tangent).

In Oregon there are no self-service pumps, as you're not allowed to pump your own gas. This scheme apparently was designed to help employ displaced timber workers. The guy had filled my tank and I'd been inside to pay (another part of the minefield - knowing whether or not you're required to pay before filling your tank!)

Now I'll shut up....