David and Frank, I think that David used the wrong word when he said to "expect some" future problems. It would be more correct to say "expect many. And Jen, there are 2 reasons that old pine barn wood is stable. One is that it has been sunbaked enough to have gotten hotter than the 135 degrees that current kiln dried pine is supposed to get to for setting the pitch and killing bugs. The other is that old growth wood usually came from forests where the tree spacing and shade canopy made for very slow growth and very narrow annual growth rings.
In today's "managed" forests, productivity dictates that you get out tons of wood and great amounts of annual growth are encouraged. This might be fine for pulp and some structural applications, but I would not want a floor made with today's white wood on the surface. The wider rings have more room for movement. That, plus less drying, are the reasons that today's softwoods move more.