It's possible that your front rotors are warping on your brakes ....
I had the same thing a while back and had to have them replaced. A shop told me that you might get to turn today's rotors about 2x before having to replace them ... The disc brakes get much hotter and the rotors probably aren't good enough to last for more than 60-80K miles. That has been my experience so far with the Contour.
Make sure that if you rotate your own tires, you use a torque wrench to properly seat the lug-nuts. You can buy a good one for $25-$30 at Sears .. or if someone else rotated your tires, make sure they don't overtorque them.
The rotors will go faster if your wheels are put on too tightly.
my 95
