Is this normal?

I bought a AP5 LT from Atlantic firearms a while back. And I really didn't look over the gun before I sent out the trigger pack out to Bill Springfield for some trigger work.

Is it normal to see a weld mark and the trigger pack? To be honest, I didn't notice it when I sent it out to him for the work. But I noticed that when I received it back. I just want to know if this is a normal thing or not?