Today I received my 4/8 norton from woodcraft.

I noticed that the 8K side is not colored eqauly throughout the stone.
There are a couple of wide streaks that are a bit lighter than the rest.
Is this normal / common?

my 1/4 does not have this.

And on one end, there is a slight gap between the 4K and 8K sides where I could slip a thin piece of paper through if I wanted.

Default advice would probably be to send it back, but as long as the stone itself is good I'd rather not send it back because I really don't look forward to do the postal service hustle.