Belly rubs on baby kittens?

My 5-mth-old baby kitten isn't yet much for the belly rub but for the past 2 weeks or so i've been rubbing it a bit when we play. By now, he sometimes gets on 1 side of his body and spreads his 4 legs a bit (mainly the front 1s) and lets me rub his little belly. Is he warming up to it and will he come to a point where he will come to me and get right on his back to get a belly rub?