Hi,

One of my girls used to suckle her sister when they were little. I asked my vet if there was anything to worry about and he said it was normal and they would grow out of it - which they did. It took about 5 or 6 months though. Maybe just try to discourage it by gently moving her away and distracting her with playing. I'd agree, as long as there's no skin irritation, there's probably nothing to worry about.

Nic