Good safety tip robert. One thing I do in my storage space for this is open the door occasionally and sniff. Coleman makes their fuel with a smell of rotten cabbage on purpose. It is to be able to tell that it is leaking. Also, I would recommend taking some old clothing or such and jamming it under the door. Oh, and never light a match around your storage area.
I would only think they would leak if they were stored where the temp changes quite a bit - like outside.