I think you should smoke him up. I think that would be cool. I don't know if I could smoke with my daughter at least not for another 10 years or so her being 8 and all but I wish I could be that cool. I just found out that my sister's kids smoke and I am a little freeked out about it. They are 17 and 18 and I told them I would smoke with them if they wanted but only if they are 18. So I see that one coming my way. My sister would flip if she found out.
Talk to him about it, you know you want to. Just ask what he thinks about weed if he's ever tried it.
Tell him you think so too What's the worst that could happen, this could potentially turn into some kind of father/daughter bonding experiance. Tell him you want to spend more time with him and why not watch something you both enjoy after a bowl or two. Try and show him maturity and that you grasp the concept of moderation and responsability and all should be spiffy.