HI Harris,
I think that’s because the Procedural Bump Texture uses UV Coordinates. I’d just keep watching and following along, because later you are going to be painting a Bump Layer over that and because of how those two are going to be mixed, you won’t notice that seam anymore (at least that is my theory). It really doesn’t seem to have anything to do with Scattershot and I can also not find anything you have done wrong.
If, at the end you still get a nasty seam like that, just mention it here, or in a new post and we can re-visit the situation.
