Could also be pad material deposition on the rotors. Try going out to an empty road and bed the pads in again.
Some brands of brake pads are worse than others for that - but most NAO friction work via cohesive friction, meaning the pads leave a transfer film of friction on the rotors. Akebono pads are own to leave heavy deposits but I've never had "warped" rotors from them.
However, besides from turning rotors the only way to really remove that film of friction are semi-metallic brake pads. Mercedes used to have in their tools/materials catalog a set of "cleaning" pads that were installed in place of the regular pads. You drove the car around the block or for a few miles gingerly, and swap in the regular pads.
That's why I'm not a fan of turning rotors unless they are OEM and you have access to a on-car lathe. A off-car lathe is "true" to the naked eye but there's the issue of lateral run-out. By the time you take off material to resolve any warpage or other issues, you can be close or above the max spec for thickness and introduce more issues.