Is “Redirect permanent” (301) really that hard to parse?

I just moved my blog from http://xcski.com/blogs/pt/ to https://blog.xcski.com/. I set up a “Redirect permanent” on the old location, so that anybody or anything using the old location will get automatically redirected to the new location. And for a lot of places that used to hit my blog at the old site (like rss feeders) seem to have handled the transition painlessly. For instance, NetNewsWireLite, which I use on my laptop, updated the subscription information and doesn’t appear to hit the old URL at all any more. Same with the LiveJouranl syndication.

But for some reason, a lot of them haven’t handled it correctly. For one thing, my spam load is down to almost nothing. Ok, that’s a good thing. But I also notice that some RSS feeders, like various “Planet” web sites, see a redirection from http://xcski.com/blogs/pt/feed to https://blog.xcski.com/feed, and feel like they can ignore the fact that the hostname part of the URL is different, and try to fetch the redirection at http://xcski.com/feed, which of course isn’t a valid URL. It can’t be that they have an old DNS cache entry for blog.xcski.com – it didn’t exist until a few days ago. It must be that they’re trying to be too clever, or not clever enough.