3-4 weeks sounds about normal, provided we're talking about poo. They usually pass urine and urates every couple weeks. Your snake's movements were probably more solid because you had just introduced him to a new home, and drinking was one of his lesser worries. He was probably dehydrated for a while, but sounds fine and well adjusted now.

And lucky you, getting to the tank in time. Mine decided to go while sitting between my boyfriend and I. Got pee on the blanket, couch, and enough poop for three cats all over the floor.