I had a rubella titer done when I was pregnant, and it showed that I had once had rubella, not that I had it at the time of the test. (In fact, having had it, I'm now immune.) You are not talking about that kind of test?
Hmm from what I read igg means positive for antibodies. Which could just mean your immune, but its a tough one. Did the obgyn tell you or general dr?
Rubella is not chicken pox or measles. But it can cause birth defects. Maybe ask to get retested. Did you recieve the mmr vaccine as a child? (measles, mumps, and rubella) will look it up and see if I can help you with info.