I noticed this once before, but it got me again on my prior post... so figured I should pass it on to other Blogger.com users... If you post an entry from a previously saved "Draft", the date of your post will apparently be the date you originally saved the Draft rather than the date you actually posted. This could cause some of your posts to appear out of order... like for me, where my "How long can you live..." post was posted after my "Plane Boarding..." post - but drafted earlier - so their order in my blog was the reverse of what I expected... I sometimes put a post idea in draft form a week before actually posting it - so this is relevant to me.
You can actually change the Post Date of a post... so it's an easy issue to fix... which I'll go do now ;)