There was a wave of automatic edits recently applied to old posts throughout the network, including one to remove salutations, and another to remove multiple punctuation marks.
Now, I don't want to start (yet another) discussion of whether or not this a good idea. But I have a very modest... policy suggestion: let's never ever edit old posts without adding edits to the revision history, so we can always understand what happened, at least.
That's the whole point of having a revision history. Even if you're sure that nothing can go wrong, something always can go wrong, as discussed in this question on Math.SE Meta.