I've seen the Profile visitors long time ago - at least two years - , but they are relatively harmless bots unless you post something in your profiles that would be useful for the bots to dig up.
What I am referring to is not a bot it's probably a human with some interest - what interest we'll see - perhaps a scammer trying to get pictures that are not yet published on the interweb or something else... We'll see.
Just be aware and awake.
Cheers
Uli