Overtorqued the lug nuts?
I had my brakes inspected a few months back by one of those "brake shops" and the guy doing the work seemed to get a kick out of zipping the lug nuts of with his air tool. Noticing this, I asked him to hand torque the nuts when he put them back on. Of course, his answer was that this tool is set for low torque so I shouldn't worry about it. I still insisted that he hand torgue them.
Over the course of the next few days, I noticed a distinct shimmy at braking. It finally got bad enough that I decided to do a brake and rotor job-it was about time anyway.
I practically had to stand on my tire iron to get the lugs off-took me about 10 minutes to get wheel #1 off. I guess the jerk ran them way up then pretended to hand torque them and in the process warped the rotors. I guess they train them that way to create more work for themselves.
Your post implied that you had had some work done recently-I'd check to see if the wheels weren't over tightened.