Sounds a bit like the brake shoes stuck to the drum... did you put the car away wet? Sometimes it happens if the shoes/drum or pads/discs corrode together. The iron content of discs and drums is high so they tend to corrode easily. I always leave the handbrake off and the car in third gear to stop it rolling, but the garage floor is flat so that works for me. You could perhaps use first gear or reverse if you are on a slight slope.
