Here's a picture of the rotor that shows the abnormal wear that lead my mechanic to think it could either be an uneven rotor or a sticking caliper.

DSC_0232 by MikeandGabby, on Flickr

The wear is not present on the entire rotor, just a section (about 1/3).

DSC_0238 by MikeandGabby, on Flickr