Recently active topics in Twitter tagged with cache

I have noticed that I am missing many of my friends' twitters/updates when I view them on my twitter home page. If I go directly to a friend's profile page and, for example, they have 4 twitters, I will only see 2 or 3 of those in my list. Why??

Title says most. Twitter (caching to blame?) shows "X-A" tweets, reloading shows "X-B" tweets, alternating. Worse: each swap appears as new to syndicators. Continues ad infinitum.

First noticed problem while using Twitter Sync. Problem appears reproducibly on twitter.com/tollie (when not logged in) and via the RSS feed.

Does not seem to occur on home page.

To clarify:
twitter.com/tollie (and RSS) eg...
Version X-A
* Tweet 5
* Tweet 4
* Tweet 2
* Tweet 0

reloading produces:
Version X-B
* Tweet 5
* Tweet 3
* Tweet 2
* Tweet 1

twitter.com/home (logged in) Archive View shows:
* Tweet 5
* Tweet 4
* Tweet 3
* Tweet 2
* Tweet 1
* Tweet 0