Post edit time stamp question

I noticed the last post I had to edit, it placed a 'edit on' stamp at the bottom of the post. I found that odd because it never happened to me before since we got on the new LH. So, I went into another post I made to see if it would do the same thing. Just 'saved' it without changing anything. And, that one too received a edit on stamp.

Later, I noticed later somebody else had apparently edited their post. It appeared to be edited because of a all caps "EDIT" written in the post. Yet that poster did not have a "edit on" stamp at the bottom of their post.

My question is, why am I receiving that stamp and other posts that appear to be edited are not receiving that automated stamp? :curious::confused:

EDIT: Edited to show what I am talking about.

EDIT 2: Not showing now. Strange.

EDIT 3: Just tried it on another post by adding in a extra period. Didn't show time stamp. Whatever that was, strange, appears to be gone now.

EDIT 4: Never mind. I think I figured it out. Saw some other time stamps. I am feeling stupid now.

One thing I noticed is that if you go to edit your post in the advanced mode, it doesn't put the stamp there. It also doesn't do it if you edit it real quickly after initially posting it. It's handy for me, because I often have to edit a typo or two out of there that I didn't notice before.