I keep mine in the laundry room too.
Bad idea, IMO, for a couple of reasons. First, laundry rooms are a frequent site of water leaks in the home (usually resulting from a hot water hose bursting, which is why the better ones are wrapped with braided steel). Since the valve is inside the washer (no one turns the primary valve at the piping off, right?), a burst hose means water spraying everywhere. Not the best idea, even if the lens is technically weather sealed.
Also, laundry rooms are generally pretty humid. Long term storage in high humidity can result in fungus inside the lens (apparently, mycetal organisms find lens coatings tasty - I wonder if Canon's SWC tastes even better to them?).
I'd recommend reconsidering your storage location. Personally, I store my lenses in Storm hard cases with desiccant packs inside (the color indicator type, and I change them out when they reach capacity and turn pink).