It is a sealed bearing. They hold up much better than the old non sealed bearings that were common many years ago. Much better. If you got the bearing very hot, you may have either damaged the seal or melted the grease. It is possible that you have damaged it enough that it needs to be replaced.
The way to keep the drum from sticking in the future is to smear a little anti-sieze on the hub to drum mating surface especially around the hole. You can do the same at the drum to wheel mating surface. Use it sparingly so that you don't get any on the brake friction surfaces.
