To me, a slip/relapse starts with the thinking process. If I'm going down that road, if I'm thinking about picking up,(I know we will be thinking about smoking), but thinking about actually giving up all I have quit for, and trying to rationalize why I should, I am on the road to relapse. I need to get out of my head, get in written down, and ask for help.
In my opinion, a slip/relapse, is just one. Ask a recovering alcoholic if just one drink counts as a relapse, or ask a recovering drug addict if just one hit counts as a slip, and if they're being honest about their recovery, they will answer not only yes, but absolutely, just one is a relapse.
Who cares what the quit meter says, we all just have today. If it starts over at zero, so what? At least you are trying, and that's all any of us can do.