brake problem

A friend had her front brake pads replaced by her brother and within about a day it feels like the front rotors are warped. They were already aftermarket Brembo rotors and I don’t think they were prepped at all before new pads were put on. I've heard mixed feelings about having rotors turned before new pads are put on. I've had no problems with just sanding the rotor and reusing it. I don’t think there was any break in period done either. So can new pads cause rotors to warp very soon after install? To fix it should I replace rotors AND pads or could I keep the new pads?
BTW this is on an 03 Civic, sorry but I can't find good knowledge on other forums. The rotor is held on with a screw so I'm pretty sure it stayed in place during the pad change.
 
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