Playdate!

So, Sweet girl is having her first, official, after school playdate as I write. She has been to playdates, and has had friends over, but always on the weekend or with neighbor kids. This is our first friend from school. When I asked her if she wanted to have someone over, she was so excited. I expected her to pick one of the girls in her class, BUT... she picked the cutest little boy, who she plans to marry one day (she offered him 100 cookies to be her husband). They are having the best time, incorporating leggos, matchbox cars, and polly pockets. But my question is: What is my role in this? I've sent a snack down, complimented their creations, and checked on them a few times. I guess I'll just sit back and enjoy it, and check on them every once in awhile!
Next year, Sweet Girl will start Kindergarten. I can't believe that she's already crossing that milestone. It seems like just last year when I was pushing and pushing for 4 hours, and finally getting to hold the sweet little child that broke my tailbone as she busted into the world 26 hours after she made her initial move. Wow.... time flies!