I don't think your baby Russian should be allowed to get much below 75F degrees, so yes, I think you need some sort of night heat.
I think Tom missed the part where you said your tortoise was a hatchling.I asked a similar question this morning about a baby Greek in a tank with an overnight temp of 65f and I was told that was ok?
I think Tom missed the part where you said your tortoise was a hatchling.