You're probably right; I don't know. I use it b/c Stef used to. I figured it was a cutesy thing.
Historically, groups like the Whigs and Austrian economists have adopted pejoratives as their proud namesake. Recently, we've seen the "proud to be a teabagger" memorabilia, for example. I like how stefbot sounds, it's ironic ... It works on a number of levels, but I would never want to offend anyone with it.