No experience of the car but I'd do this:
Dissemble clean and check - probably nothing to see, but a good idea in any event.
When you re-assemble put a thin smear of copperslip on the backs of the pads, and any pins they slide on. If things are sticking, this should fix it. Take car not to get the grease on the disks/drums, friction material or rubber components.
The Gomog link is useful, but does not detail this problem.
