profsnl_killer 12/23/2012I had a problem like this on an older truck, several years ago. The rubber brake lines going from the frame to the caliper/drums had a corroded interior liner, which would collapse when the fluid tried to return to the lines after releasing the brake pedal. The more times you pressed the pedal, the more pressure that was built up inside the caliper. try loosening the bleed-off screw to see if it relieves any pressure and tighten it back up. Loss of a little brake fluid is not going to hurt the pocketbook to eliminate possibilities if it isn't the problem.