Most likely there was moisture either on the reels or in the air in the tank. Sitting there for three days, the emulsion on the film absorbed that moisture, causing the film to stick in the channels of the reels. When you started the development process, the developer and other liquids weren't able to be absorbed into the emulsion because the stuck on reel got in the way.
You do not necessarily need to put the film back on to the reels to refix and wash them, but you can. The entire process can of course be done in the light as well.