I noticed that too, I wouldn't be shocked to find out Machida added some rubber-guard work to his game......He may have had it all along his ground game is pretty impressive from what I know of the guy.
But I couldn't tell if he was attempting to pull rubber-guard or was just looking to sweep Rampage with a omoplata because he sort of slids out to the side more then you would expect from someone trying to lock in rubber-guard for defense but that could just be do to possible inexperience with it.
Would be nice if someone asked him about it to find out if he was going for an omoplata or was trying to hold rubber-guard to defend the GnP.