I guess so. If I touched my wife's upper lip gently with my finger she would freak out because it tickled her??? I think I only got ticklish if she caught me off guard by poking me in the sides so I guess some are more ticklish than others.
Oh yes. And you have to know how to touch someone so as to find that out. The best way is to firmly plant hand instead of gently swishing hand with feathery strokes that will send a ticklish person through the roof.