I'm not ready for this...

Elijah is 2. Up until now, pretty much all of his play with other kids has been at daycare, church, playgroup, or playdates with kids of my friends. Now, he's friends with the little girl who lives in the house behind us who is 6. I'm totally fine with this, except I just find it so weird that he has a friend over whose mother I don't know really well and whose mother is not over at the same time for a visit while the kids play. I wasn't expecting him to have a friendship like this until he was at least 4.