There are real items to consider for cold weather curing. Anecdotally, my pool was shot (dry-mix) on a day when the high was 27 degrees and maybe the low 30's the next day and thereafter (and the ground was frozen). They heated the water coming out of the truck in a rudimentary fashion (more to keep it from freezing than making it very warm). I'm not sure what if anything was added to the dry mix. No problems developed. Certainly your ground temps are well above freezing, probably by 15-20 degrees.
For me, I wouldn't be concerned but I'd ask what precautions they will take. And how you would notice if the concrete was affected. At least it shows you are interested. There is a warranty - such as it is, on the shell.
Just my personal, non-professional thoughts for your situation.