I've had this happen too - with each and every one of the 50 stars of Carol Doak's pattern. I found when I started removing the paper before sewing the sections together and then using a scant seam, things improved.
But if I sewed the sections together using the lines on the paper, I got a full 1/4" seam (or more) and then the finished block was too small.
Now, I always do the sections, trim and remove the paper. Then I sew them together just like they were non-paper peiced blocks. I have so much better luck getting everything to line up correctly that way.