These four lines are the contents of several Atom elements that should not be displayed to readers of the feed.
As you said, your feed is valid, and furthermore, I don't see anything obvious wrong or even unusual with it.
I've reported this to a friend at BlogLines.
P.S. Nice use of & in the title of the previous post.
I've been noticing it on certain blogs myself. I'm always getting a bytehead at the end of my own feed with Bloglines, although that seems to be coming from the beta of Blogger. I think.
I thought I would try to validate my feed just to see what's up, and the validator is throwing 500's. I can't see anything else myself about any of the feeds that are causing Bloglines to do that.
I don't know what you or Bloglines fixed, but your feed is showing like it should now.