I would retake for low scores in RC and QR. An unusually low QR by itself may not be too big of a deal, but I'm combination with the low RC I think it's definitely in your best interest to retake.
Although RC is often said to be the most indicative of success while in dental school, I've seen people on here report getting interviews with low RC score. QR is not a major concern for schools. I personally wouldn't retake.