I played around with it a bit more and every other stitch I did in triangles had the right normal. Nothing I could do in the middle stitches (clockwise or counter-clockwise) would get the stitching to have correct normal.
I don’t know the meaning of the word “stitching” as you use it (not being anglophone, you know…). Since you’ve had success in many cases I’d suggest that you just invert the normal where they don’t agree by selecting those faces (actually the vertices that make the face) and WKEY>Flip Normals. Sometimes ctrl+n (recalc normal outside) and ctrl+shift+n (recalc normal inside), when applied on selectec faces, can proove useful. All this is good inasmuch you don’t have to deal with too many rebel faces.
I don’t feel like I’m helping much. As you said first, it may very well be a detail, which I miss to notice too. Maybe someone else will put the finger right on it.
And oh yes, I’d bet that Blender likes you : it just have the strangest ways to show it at times…