I agree completely Nigel. I have a page http://catalogautomation.com/9-things-probably-wrong-with-your-catalogue/ which is specifically targetted to encourage downloads of my e-book. If a user closes the popup the first time they visit the page I think they would be expecting to be able to get the popup back again by refreshing the page. Fair enough that you don’t want to be annoying people, but on some pages it’s actually worse not to invoke the popup each visit.
If there’s another similar feature then this should be obvious 