Sometimes a block can stretch one way or the other when ironing, making it not end up square when actually there is a 1/4" seam allowance and it's fine-- but then if you go to square it up, it doesn't help a thing. With several triangles in this pattern, it's easy to be a tad off when ironing because of the bias. However, when the block is sewn into the top and re-ironed you find it all works out fine.
The general rules suggest to welcome all skill levels. And the swap is for fun, to sew together for fun. :-)