I haven't seen mention of it yet, but I came across it today and thought it worth posting.
There have been waypoints added to a few places, e.g. Plains of Ashford. I had 100% previously on one of my alts only to find him at 98% now, missing a waypoint. This wasn't on any of the maps on the wiki that I could find, but after poking around I did discover it was way down south in a previously uninteresting area. It seems these new waypoints are connected to the new guild missions, and as such it's pretty tough for a level-appropriate character to get there safely by themself.
Also, while tripping the new waypoint did take me back to 100% from 98% I did NOT get a second map completion reward. Just FYI. It does seem to count towards 100% world map completion, however. --- www.rptools.net 100% FREE virtual table top, adaptable to any RP system.
GW2 Wiki's patch notes added footnotes regarding the two new waypoints.
They DO count towards zone completion, and towards ultimate map completion - BUT! - someone who already has 100% map will NOT have that status revoked. They have their title, their achievement, their rewards, and the associated rewards for the zone completions.
So, you don't get anything for re-completing, other than the XP for discovering a new waypoint, and for having the zone say "100%" again.
(That reminds me... I still need to grab the one over in Brisban.) --- "As the good archmage often admonishes me, I ought not to let my mind wander, as it's too small to go off by itself." -Danilo Thann