For me, I'm not sober if I have used drugs or alcohol. Sobriety is not a state of mind for me. It is simply a fact of whether or not drugs or alcohol are in my system. I may be thinking all wrong and even have plans to drink again someday, but I am still sober if I have not drank.
Even when I was running in a different program, the term "relapse" never made any inner sense to me. When I drank, it never felt like anything other than a conscious decision to drink. "Relapse" almost made it sound like it was an accident, or that I didn't mean to do it. I actually hate the term now that I think of it!