Haha, mine has done it since he was a baby. He was abandoned by his mother at a few days old (his eyes were still shut). I actually hand-fed him when I was 12 and raised him. Now, whenever he sees me, he starts to drool. He doesn't do it to anybody else.
oh well... my cat started the drool thing last year. maybe she has something about being seen as a grown up. She will play with my erasers up untill she realizes that I am watching her play. Then she just stops, huffs, and walks away.