Trust me--they don't have to be expired to start leaking. (Costco batteries that started leaking In Their Packaging that I just got rid of, I'm looking at you.) Your best bet for stuff like that is to remove the batteries before storing.

Also, you don't necessarily have to throw out an item in which the batteries leaked. You can get rid of the mess with white vinegar (use a q-tip so it doesn't get everywhere), then wipe lightly with water (with both of these, obviously you don't want the liquid getting into the housing). Anyway, I saved a few remotes this way.