As tinita already said, the 'fixing of typos' a couple of minutes after the original post would not be marked.

Then, some more minutes later, only the last edit would be automagically marked, and by whom the edit was (could well have been a janitor).
Thus all you'd ever see was that the node was later edited (i.e. not exactly in the state it was in when first written).

This puts just a little pressure on authors/editors to sometimes note what they've changed - and why.

Cheers, Sören