Both my 4 yr old or 6 yr old fill a pull-up at night (both were daytime trained around 2). We don't worry about it although I think my oldest would like to be dry at night. We tried various cloth night time pants, but they often leaked and always gave them a bad rash both front and back, anywhere the pants touched, I think from the acidicness of the pee. So, we use disposable pull-ups. Sometimes I've wondered if I did something wrong as so many of their friends, including a couple 2 yr olds we know, are dry all night. But I think it must just be their plumbing and the fact that they are very deep sleepers. It must not be that uncommon judging by all these responses.