Cracks thru out the house

I hope someone could help me.
My house (end unit 2 car garave townhouse) was completed in Oct. 2002 and we moved in the first week of October the same year. We've already had our one year warranty work in October 2003 and at that time, the builder did all the necessary things that is usually done for the one year warranty work. They caulked all the cracks along the stairs, nail pops, and re-touch up,, etc...
My concern is that the cracks along the stairs are coming back again, and this time, and cracks at some places are pretty wide. I've contacted the builder and the response I got from them was that becuase our house is no longer under their warranty, unless the cracks are more than quarter of an inch, they aren't responsible for anything.... My question is, is this normal for the house to have cracks all thru out the stairs? even after the caulking and touch up?
I also see some cracks on the walls as well, not a big crack, but is making me nervious... Do I need to just take care of this from my end?
I'm just lost and worried......

 

It's your house settling. I have the same cracks along the staircase and I'm going to be cauking them soon. Run a bead of cauk and use your finger to smooth it out.

-Teak