It can be either general corrosion built up on the brakes and / or the handbrake seized on.
General corrosion on the brakes should clear itself after a short time.
WHS. If I leave my car for a week the disks start to rust a bit. After a short drive using the brakes regularly and smoothly the pads clean the rust off and bite the discs better. That said, 10 weeks is a long time. I'd be tempted to clean the disks up with some medium wetordry paper first.
Another thought. If your car is still under manufacturers warranty they might give you new disks. Subaru did for my Forester.
