He's greeting you! That's a healthy behaviour. Enjoy it. I nearly break a leg trying to get in the house when they both rush me as I walk in the door. They are just happy I'm home or their trying to kill me!
Actually kittens do this when they want food/milk from their moms, when momma cat is trying to wean them,the kittens weave around trying to trip her up cause once she falls over and a bunch of kittens attack her nipples, she basically sighs,lies there and lets them..so basically your cat sees you as mom I guess