As a long arm quilter, I have learned to ask before quilting. One time I had a quilt for a lady, and one of the blocks was sewn - wrong side of fabric showing - of course she wanted it back to fix it. Had another one for sister and she had one block turned the wrong way. asked her and she said just leave it - her humility block (she's a quilt teacher and she now uses that quilt as an example of 'when you are tired, be careful - things just happen'. Usually start conversation with ' I like the originally you put into your quilt by making one block different'. This gets their attention and you find out quickly if it was meant that way.