We've discussed that a few times. My theory(unproven of course) is that the places that have posted a 30.06 sign but not the 30.07 is that the .06 sign was posted well before open carry came into effect and they haven't bothered to post an .07 sign.
Now if it's a new 30.06 sign, wulllll I dunno.
Your guess is a good as mine.