Yes we have entered that phase. Well, it's actually almost never whining - we end up saying "no yelling" a LOT more. E's just an aggressive little dude. I think he gets it from me... whoops! :S
Anyway, I was just convicted this morning that it's totally hypocritical of me to tell Ezra not to whine when I'm whining all day long. It's the little ways that the Lord (somewhat) gently says, "Grow up." I feel encouraged to say "No whining, Mommy" out loud when I catch myself. That way Ezra knows that rules apply to us, too.
Do you ever catch yourself not obeying the rules you set for your kids?