I was pretty positive it was. Had never seen or heard of a cursive Sidney O by itself like that before.
They were asking $70 and I wanted it, but had already just picked up a #10 ERIE and couldn't swing it. This place also had a couple of other Sidney Hollow Ware (actually said Sidney Hollow Ware) skillets but with bows. Broke my heart!!!
Sorry, had to edit that. I actually said a #9 ERIE by mistake, but was thinking of another gorgeous pan I saw there.