Yes that is normal,standard folds form a very slight cascade due to the way the rods and rings stack on each other when the blind is pulled up. The calculation of the rod pocket positions means that if the rods were all pulled up to exactly the same height, all the folds would be exactly inline. (see image)
However that is not how a blind pulls up, the rods and rings stack on each other on the cord which creates a very slight cascade. If you were really wanting to make the folds line up exactly inline you would have to make make an adjustment to your rod pocket position calculation . It would involve making a mock up to see what the slight cascade depth is caused by the type of rod pockets and ring/breakouts you are using. Then recalculating the rod pocket positions to adjust for this. (this is not something we do)
Thank you for your great tutorial. I have to make 4 Roman blinds using patterned material, should I cut the face fabric for all the blinds at the same time at the beginning of the project or as I go?
When I make up several blinds in the same fabric I tend to cut the face panels all at the same time to ensure that they all start at the same point in the pattern, as this avoids confusion later.