Shackle angles can spiral to a whole new internet of information but in general what you're seeing is probably totally fine. Leaves get longer when they are compressed and will push the shackle back. And the other side is that when the spring droops they pull forward a little. Being a few degrees forward isn't a problem.While on the topic of front shackle hangers. I got a quick question. Mine while bolted to my front leaf springs they don’t sit straight down they are a little diagonal is that normal/ok
And to relate this to this thread, one of the things to watch out for is shackle motion with headers, lots of headers are in the way of the shackle especially when you start creating more wheel travel and especially when you use the truck and put some wear on the bushings.