Hi Angela, they sound delighful.
I have a book on dwarf hamsters and in the reproduction pages, it states winter white babies (P.Sungorus) are not sexually mature until around one and a half to two months of age, so I imagine the babies do benefit from staying with their mum for a little longer than three/four weeks. I know it does with baby mice although male mice are sexually mature earlier than this.
It helps them to mature better and learn behaviours that they may miss out on if taken away from their mum too early on. There are breeders on here who will be able to correct me on this of course as I`m only stating what I have in front of me.
How many wee ones do you have? Were they a purpose bred litter or accidental? I love winter whites. x