My adult female just had a litter of four cuties.

One of them, the little, albeit CHUNKY male, has started making a "purring" sound, just like a cat.

It's the darndest thing I've ever heard and I was wondering if anyone else has ever experienced this or heard of it? I can't seem to find anything while doing a Google on it so I decided to throw it out here. BTW, the babies are just 17 days old. Thanks a bunch!