I can tell you it is the 'normal' behaviour of b2e.
If it is the behaviour you want, that's a whole other story.

In my blog, I created a new function, next to 'publish now', a 'publish'..
I have not created that function yet for 1.6

2 things to think about here. First off, the 'publish now' feature uses the current date/time for the publishing date and time. That'd be the "now" part of 'publish now' eh? To remove a post from deprecation edit it and change the status to 'published' instead of 'deprecated'. Second thought: I'm not sure if this will help you if you are using version 1.6 because that version has a problem with 'modified date'. Or one of the date stamps each post carries. What happens is that each visitor ends up updating a particular date stamp which implies a new modified date. I believe there is a patch for this in the "bugs in 1.*" forum, but I could be wrong on that.