It might be a "stretching" problem. If you are using triangles to make your geese, they are far more unstable and tend to shift as you sew. There are a few different methods out there that use a rectangle base and two squares in the corners so you don't have to mess with triangles. My beginner students find this method to be the easiest for accuracy. Go to
http://www.allpeoplequilt.com for patterns that use this method. Hope this helps.