I understand your thinking and that could be it. BUT I have flown this exact mission at least 20 or more other times without issue. it is possible they were all close calls but I would hope that the software is smarter than that and is setting your altitude for each waypoint according to that gps coordinate. If they were the same why would that be a seperate setting for each waypoint. They could just have one.It is 160 feet above the original point of take off. So if the terrain changes 100 feet higher at waypoint 1 from where you took off you now only have 60 feet clearance.