I have heard of some snakes being able to tell humans apart as well (can't remember the species). But being fine with one person, then if another (same person every time) tries to hold it, it gets all huffy and tries to bite.
I also believe that instintual has to be SOME kind of "smarts". We started out with "instinctual" and evolved into what we are now, computers, cars, planes, and a world of science I couldn't even explain.
Neptune, Zion, Enigma,