Bright ring on case when using sizing die

[SigSavage]

I just wanted to know if this was normal, and if not, how to correct it. I have a Lee die set for my .40 pistol rounds and a Redding die set for my rifle rounds. With both of them, I followed the manufacturer's direction on how to set up the sizing dies. When I run my brass through I get a bright ring around the base of the cartridge about 3mm up from the shell holder. Is this something I need to address?

Thanks

 

[Trinimon]

Normal.