Off the Beaten Path
Join Date: Nov 2013
Location: Calgary, Alberta, Canada.
Interest: Hiking, Backpacking, Skiing, Space History
Without knowing the purpose of the flagging its hard to say if this was justified or not.
If it was some kind of survey activity, then you may have just created a whole bunch of work for someone to go and redo it all over again. If it was someone just trying to be "helpful" then sure. Personally I would have left it as is, and perhaps contacted the land manager to see if it was the result of planned activities in the area. That it has elevation details on it would make me lean towards some kind of survey or planned activity. Someone doing it just for the sake of marking a trail is unlikely to mark each and every one