One or both of your front calipers are sticking. They will do that with age and you can either rebuild the caliper yourself, buy rebuilt calipers from the dealer, or buy new ones. I just had to replace one of my rear calipers because it was sticking and making the rotor glow. What happens is, as your brake pads wear over time, the piston comes out farther from the caliper to keep pressure applied to the back of the pad. When the piston comes out farther, it is exposed to the elements (salt, dirt, water, etc.). All this crap builds up, and then you go to replace your pads and the corroded piston gets pushed back down in the caliper. Now all that buildup is on the sides of the piston keeping it from moving as freely as it did when it was new. Your calipers spring back when they are new because that piston moves free, but as they get older, they don't spring back as freely because that piston hangs up causing the pads to constantly rub with excessive force and create the problems you are having now. If it is bad enough, it can sieze the rotor completely and that's gonna get costly. Other problems will be very short pad life, warped rotors, and heat issues if the pads are rubbing harder than they should be when the brakes are not applied. I would switch those out right away if it was my car. How many miles you have on it??