My guess is as stated above it may also be the tripod...with my old manfrotto's column extended (not even all the way) and either my 24-70 OR 70-200 on there it would droop a litte bit...a lot of the time just enough to piss you off.
It was never a real concern for me as things are a lot more "easy going" I guess you'd say with landscape, most of the time theres time to recompose quickly...I dont have to worry about my subject "walking away" 
SO I guess just try shooting with the column all the way down and if that doesn't work sell your head on here to someone just starting out who might not be concerned with the droop (theres always someone looking to pick up a base model ballhead cheaper than what BH sells it for
good luck OP
