missing and duplicate entries

I read several web comics through Newsblur, and I’ve always been very happy with it. Lately I’ve noticed that not every new comic shows up, and frequently it’ll show up will have the content from an older day. A good example where it happens often is Schlock Mercenary (www.schlockmercenary.com). It’s possible that Newsblur is faithfully reporting what is in the feed and the feed is just incorrect, but since this is happening to several different feeds I don’t think that that’s the case.