Leaf spring question

[Limit 5]

02 Ranger single axel. I have noticed that the band (I think that is what it is called)
that is on the leaf springs has moved. On both sides the band has moved back 2 inches towards the axel. You can see where the original spot where they use to be.
Any idea what can cause them to move. I have tried to push them back by hand and no go, I do not whant to force them but would like to know what caused this.
Thanks

[EasternMarine]

They sometimes do move from the spring flexing. The band is just to keep the leaves from shifting position before they are installed. Once the spring is u-bolted to the axle the springs leaves can't shift position.