Is it wrong to take kittens from their mother?

I spent one summer at my cousins place in the countryside. Their cat was pregnant, one day she went off and came back 3 days and she wasn't pregnant so she obviously had the kittens, we didn't know where though she had them hidden. Anyway we heard them meowing in the ditch and I went and picked them up, five of them to bring them into the cat's shed I thought it would be better for them, whilst I was walking and holding them their mother was eying them frantically and couldn't take her eyes off them as she was walking by my side, I then put them in their warm box with their mother. Now that I'm older I feel like I was wrong to do so, and well slightly arrogant.. for future reference is this the wrong thing to do?