Parking brake light comes on after driving for an hour

The "parking brake light" is often also an indicator of a brake system warning in general. Is it a red light that says "brake"? If so, this isn't just for your parking brake, it is for your hydraulic brake system. It could be indicative of a leak or other brake system concerned that is pretty urgent to look at. Any of your warning lights that are red in color are considered emergency warning lights. I'd recommend having a look at your brake system as soon as possible. I would not drive the vehicle further until this is completed. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops