I've not seen this color in KQR as uniform as what your pics indicate, but, from KQR's mother side, seen in the pic below, she does have a tendency towards coloration late in flower.
Due to your temps not falling too low, I'd be inclined to rule out temp induced as a cause. Lack of PK in late flowering can also be a contributing factor to late flowering coloration, C99 often exhibits this. So although this color you have seems more uniformly distributed, I'd say it is coming from perhaps a combination of genetic factors and cessation (weaning off) of PK...iow, she has that ability more pronounced due to genetic factors that the lack of PK contributes in that regard. I've never known of, nor seen, what I'd call a purple Cindy, nor a purple pheno of G13bx (other than temp related)...doesn't mean it can't exist. If you have clones numbered to know next time what's what....run her again and see what happens.
Maybe you just have a killer of a Killer Queen Redux pheno.
Here's the C99 mother side of KQR I mentioned:
Below is an example of a true purple
strain (due solely to genetic factors) that I currently have going (Ace's Pakistan Chitral Kush)...note the differences....in a true purple plant the calyxes exhibit a purple trait, not just the leaves.
Sounds like you have a nice vacation planned...enjoy....great choices of travel pals.