When we first got Bingo at 8 weeks old, he was very quiet but when he settled in, he started to bark if anyone knocked at the door or walked near to the front window, especially the window cleaner.
He would bark as soon as anyone knocked and continue barking until he felt he had done his job.
he lived with us there for 12 years, then we moved here, and he never barked from the minute we moved him in, not even when someone knocked, he seemed alot calmer .
I noticed the dramatic change and came to the conclusion that it was a sense he had of danger or fear in our other house.
I wonder if your new puppy has a sense of unease for some reason, once he is more familiar with the surroundings he may calm down, but possibly he is hearing something you aren't.