Remove your calipers and check the dust boot. It has probably pulled out of the caliper in one spot allowing dirt into the caliper. We live in eastern Ontario (snow and salt) and it is a very common ailment. You can buy rebuilts from the dealer or kits to rebuild your calipers. The dust boot design is destined to fail after 3-4 years.

check your tire pressure first, we find that as the most common cause of pulling
while braking, blown belts in the tires also cause the same thing, try swapping fronts and see what happens. less common, but next in line is caster being out of specs. If you had a stuck caliper, you'd be seeing smoke. worn struts, bent control arm, strut or spindle are the last things to look at. I'm speaking specifically about the x70 series.

Normal? No. You might check your left calipers to see if they're free. Could be air in the left side circuit too. Bleed the brakes carefully and see if that helps.
--
Erwin in Memphis, '95 855t

If the car ALWAYS pulls to one side, you probably have a damaged suspension/braking/steering component.

It probably isn't warped rotors. Warped rotors would cause a pulsating similar to ABS that causes the chassis to rumble.

Check to make sure it is the road itself. There are lanes that cause my car to pull to one side ALL the time when I brake. Some to the left, some to the right.

Also, check to ensure you don't have a seized caliper, or any other brake problems.

And don't worry to much about rust. Volvo uses a non-stainless rotors for a reason. Stainless is more prone to warping. And rust is scrubbed off after the first or first few applications of the brakes.