Sounds like a warping issue.
Turning the existing rotors will alleviate the issue now, but it's likely to return once they get nice and super hot again. Also, your stock rotors are vented. Vented refers to the gap between the two braking surfaces that looks like it has "fins" connecting the two sides. That's a vented rotor.
I think you meant to refer to a slotted/dimpled/or cross drilled rotor. They're nice, but only if you spend good $$$ on non-Chinese made rotors. Cross drilled have a tendancy to crack between the drilled holes, and that's just not good at all.

Lots of good brake replacements out there, for almost every budget. But with any metal...if you get it hot and it cools, it's likely not to retain it's original structure/shape/dimensions. If you are going to replace, make sure you ditch the pads as well as the rotors.