Grove in center of both front brake rotors ?

[full foot notch]

Was working on the truck and was trying to see if the spindles on my truck were CPP or not since there's a CPP spring kit all around. I noticed this grove on the rotor and first thought was aww F I've gotta take apart this truck to replace the pads and rotor, so I looked and saw that the pad has plenty of meat on it. I ran my finger nail over it and it seems to be a machined groove and not something akin to a bad pad. I checked the passenger side and it too had an identical groove in the rotor, I tried getting digital calipers between the wheel and rotor and seems about 1 inch down from the outside edge. I've heard of slotted rotors but not with a single groove. And since it's identical locations on both front rotors my mind tends to eliminate that it's bad pads , the second appearing line nearest the hub is just where the cast part of the rotor meets the machined surface , it's not a line at all

Here's a pic of the rotors