I agree, you've probably got a caliper that's seizing on the rotor. There are steel slide pins that the caliper moves on when you apply the brake pedal. If these get corroded, the caliper will stay in contact with the rotor and overheat, eventually warping the rotor. Fix this soon or you'll be changing rotors too. Take the car for a spin, using the brakes normally. Pull over and feel (don't touch) the front wheels. If one is really warm and the other much cooler, that's what's sticking. They will stick on, not off. In an extreme case, you'll see lotsa smoke from a sticking caliper.
They are probaly rusted so replacing them would be best but only if they are badly corroded. The hardened polished steel needs to be smooth but a simple wire brushing might be sufficient. Make sure you check the rubber boots on the sliders and be sure they aren't torn, letting water etc. in. They should be greased with a high temperature, silicone lube.
Have you ever flushed and refilled the brake fluid on the vehicle? I do this every 100K on my Saturn Coupes and the fluid that resides in the calipers and sits there for years gets pretty nasty. The fluid can actually degrade over time.
I'd try that first before condemning the caliper slide pins or the calipers--at least till they are inspected.
If the folks doing brake work on your vehicle have been competent, they should have kept those slide pins well lubed and the boots intact when doing pad replacement.
Also, sometimes the pistons don't retract as they should after many years of use....