Backlog doesn't always clear on the reference installation

[EasternPA]

I try to retain only a few articles from the last few days in my reader, but when I delete all articles from a given feed, the feed often reloads with articles dating back to before the earliest dates I want to see. I want to help you keep your server costs down, but you're retaining articles that are over a month old in some of my feeds.

Is there anything I can do to force your reference site to delete articles that appear stuck on your side? I don't know how many regular users you have, but if this happens across hundreds or thousands of feeds, you may be paying far more than you need to on storage.