Should I put my 4 yr old daughter in vocal classes?

I would like my daughter to have an extra-curricular activity, she seems to have a natural "pick-up" for music. (My husband is a musician and I used to sing, stopped when I became pregnant.) Her and my son actually, both pick up lyrics to a song ver very quickly, and their pitch isn't perfect, obviously :-), but you can tell they are trying and for whatever reason it just comes naturally.. Should I keep guiding my daughter and having fun with her doing it? I don't want her to lose that interest yet not push her ..