Yes, they do. All the time. I used to teach international patent lawyers German, and it's quite mazing how much you have to check in order for your own design/invention to be legal.
Again, you obviously cannot copyright the actual setting of the blocks, but you can copyright your instructions of it. It would help if you can find out the name of the person who used that type of setting, contact her/him, and ask if it was their original design or if they had seen it somewhere before. You can then include that information in your instructions. It's also possible, of course, to say in your instructions that the project is based on a design that has been around the quilting world for some time, that you unfortunately don't know the origins, but that the instructions (and any pictures) are your own.
A little story here: Some years ago a very large US retailer used an image of a needlework Christmas motif in all their stores as part of their seasonal decorations. They did not check out the copyright situation. The designer of this piece of needlework took them to court, and achieved a very high settlement that she donated to charity. Rumour has it that it was a 6 figure sum. If they had asked her, she probably would have given them permission for a couple of thousand $$$.
Lorchen