Kerrdog

I started loading my own 7MM Rem Mags. I'm using brass that I have owned for several years... saved it for the time I would do my own loading. This is factory brass, first time reloaded. I bought a complete kit and all the dies I needed. 7 Mag is only one caliber we reload, but it is the first rifle caliber we've tried. I began with a full length sizing die. After the initial run through the press I saw these dimpling marks on the shoulder. They were positively NOT there before they were resized. On a few, I tried a collet die after the FL die to see if it would remove the dimpling, but it didn't. Is this something to worry about? Will it fireform out? Should I toss it all?

Thanks for your help.