Take a look at this lifter, please

The grooves in it are not that bad, but you can feel them with a fingernail. I checked the corresponding cam journal and its perfect, as are all the rest of them.
I've got a new lifter that I'm putting in, but was wondering what would cause this. I used the original dogbones and bone-holder. I suspect it was some debris that got caught between the lifter and the cam.
What do you think?
Thanks







