Can my house be "too tight"?

Yes it can, but it's highly unlikely, especially in the windy climates of the northeastern United States. Wood framed homes will always have some small gaps and cracks no matter how well they are framed or insulated. Windows will also have small amounts of air infiltration. Whenever a door is opened to the outside of the home air exchange occurs. Our position is that you only get one chance to insulate a new home. If you under-insulate you will regret it for as long as you live in your home because you can't fix it. In the event that you over-insulate and make the house too tight, the situation can be remedied with low cost ventilation. The motto in the foam industry is "insulate tight and ventilate right."