After upgrading to 126.96.36.199 Build 15, I have several APs that are root APs showing up as connected with a status of "mesh forming". Some of these are at sites where there is only a single AP so no mesh APs have been deployed. The site seems to be functioning fine - I have just never seen this status in the past.
There is nothing in the User Guide regarding this status from what I can find.
Oh - one last thing - some of these APs have been in this state for more than a week.