Reflex can vary a lot it seems. I don't have mine done anymore because it sends me in a huge flare but when I did sometimes they could get one and sometimes not. If I was tense etc it threw off the result. That is why they want you to be relaxed which is impossible for me when someone wants to get near my pain. I am not saying you should not look more into this just my experience. None of the doctors I have seen have been concerned with lack of one if they did not get it etc. Again not saying you should not look into it more.
When is your next apt? Could you call the nurse even at the office and ask your question if concerned?