NBA total quarter lines

I briefly scanned over the games the past couple of nights and noticed that in probably %80 of the games the 1st and 3rd quarters where under and the second and forth were over, my thoughts were that the players had not "warmed up" yet for the first quarter and were a bit tight coming into the 3rd from the half, and the 2nd and 4th were mostly over because of being in the "groove" and warmed up, any input or am I seeing something thats not there? :)