I do home inspections for work which includes a fair amount of new houses. It's VERY common for detectors in new houses to alarm when I get in and start running the heat system and testing the appliances. There's a lot of dust that lands places during construction and then gets blown around for a bit. Also, lots of off gassing from finish coats on appliances, heaters, etc, etc. As others have said, replace the detector and just use the coach. I'd say there is a very good chance it will just go away after some time and usage.