On the way back from a show Saturday, my front disc (driver's side) brake wouldn't release and started dragging on the rotor. With my foot off the brake, it tried to pull (hard) to the left. When braking, the pressure evened out and the car tracked straight. Fortunately I was within a few blocks of home and didn't cook my discs. It was extremely hot that day so I hoped it just needed to cool off.

Wrong. I just jacked the front end and the driver's side will spin by hand, but it is dragging pretty heavy. I can't find this symptom in my trusty repair manual.

Anyone know what this might be or how to fix it?

 

It sounds like your piston in the caliper is sticking. You might be able to rebuild it or just replace it. I would do something with it soon though,or your piston side pad will wear pretty qiuckly.