It looks healthy to me. I have a few different acros that really show their polyps at night. Also in my experience new frags can take a bit to extend polyps. Keep an eye on it but for now it looks happy and healthy.
It looks happy in the pics. It's not in-common for corals not to have PE during the day. In the wild they only open up at night when the food source is available and to be safe from predators.