I believe junctional rhythms are kind if like a protective mechanism when the heart rate falls into your area. I believe its normal only in a sense that the protective mechanism is doing what it's supposed to do. Are you seeing a physician about this? That is a very low heart rate.
These junctional beats sometimes occur in athletic, young adults during the sleep cycle. You didn't mention your age. At the other end of the spectrum they can also present themselves in people with sick sinus syndrome. Just as long as your physician is aware of them. Curious though: How did you know you were having them?
I don't honestly know if this is "normal" or not. My guess is that it's not normal, but considering your age, is acceptable. I would continue to monitor this. You and your physician are aware of it, so let him make the call.
Recommend Adam to read my comments to tom_h