I bought a big lot of hot melt edge banding at an auction for almost nothing. It is more than I will ever use, so I am thinking about putting it up on ebay. It is all in retail packing, but some of it looks pretty old. I don't want to sell something that doesn't work. Does this stuff have a lifespan? I can't imagine why it should (hot melt glue is just polyethylene, isn't it?) but want to make sure first. Thanks.