I have pressed seams open a number of times on quilts in order for the seams to lie flat. The quilt police hasn't found me yet! In fact, I don't even think about the quilt police anymore--it's my quilt and I'll do it my way. Now, the only problem I had when pressing them open was to make sure I backstitched at the beginning and end of the seam. I don't know if it's something else I did wrong, but seams that weren't backstitched starting to come open and I had to restitch each one.