Only you can answer that question. If you developed, washed and dried the film in a clean environment I don't see why storing film in a developing tank would make it more dusty. I would think it would be the opposite since it is a sealed container. If there was no dust in there when put the film in there will be none now. Rewashing film creates new opportunities to screw up your negatives. I wouldn't do it unless I was getting rid of water marks or something like that that won't come of with some canned air.
Ghostman is right. No matter how meticulous you are you will have dust specks that show up on your scanned negative. Before I scan I wipe all my work surfaces and the outside of my scanner down with a damp sponge. Be sure to stock up on canned air and get a soft lense cleaning brush or similar to knock dust off your negatives. Sometimes canned air doesn't quite get the job done. Don't be annoyed if there are a few small dust spots. They are unavoidable. After scanning you will need to allot some time for a healing brush PS session.