Yes BanjoRay, and many folks'd say that you should cock your thumb on the string it's going to pick next.
I'm in the same boat as Matt Milton. I taught myself 34 years ago and never cocked my thumb. I realize, after conversations with super banjo players like Coole, that I should, but it's too late to change what I've been doing for so long. I do, however, insist that my students do it properly.