Why would it be creepy for someone using a social networking site to search for people they've met over the years? Also, how much of the perceived "creepiness"

Why would it be creepy for someone using a social networking site to search for people they've met over the years? Also, how much of the perceived "creepiness" of someone searching for someone on LinkedIn just a variation of this: http://thedoghousediaries.com/1042 http://thedoghousediaries.com/1042 ?