Hi booklady,
Not likely. The store window "should" never really become cached, so it is more likely that the problem was resolved between when the original post was made and I reviewed the OP's account. I've just handled a few similar cases in the past for which clearing the customer's cache has resolved the problem, so I included that suggestion just in case.
If your Sellathon gallery is showing expired items, it is probably due to something other than caching issues. If you experience that problem again, I recommend contacting Sellathon's customer support department using the webform on the following page: http://sellathon.com/support.html
-Mike